CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2007
Manolis Vavuranakis
SUMMARY 1Acute coronary syndromes are mostly the result of coronary plaque rupture. Diagnostic techniques focusing on the early detection of those plaques that are prone to rupture are still limited. Increased neovascularization in the adventitia and within the atherosclerotic plaque have recently been identified as common features of inflammation and plaque vulnerability. Contrast-enhanced intravascular imaging with microbubbles can be used to trace perfusion. 2In the present study, we examined the perivascular network of the left anterior descending coronary arteries and left circumflex arteries of four domestic, clinically healthy pigs using intracoronary ultrasound after injection of microbubbles with a differential imaging technique (ACESÔ; Computational Biomedicine Laboratory, University of Houston, Houston, TX, USA). Our aim was to detect blood flow into the coronary lumen and perivascular flow in contrast-enhanced images. Eleven regions of interest (ROI), including perivascular structures, were compared with regard to their grey scale level before and after the injection of SonoVue® (0.06 mL/kg; Bracco Diagnostics, Princeton, NJ, USA). 3A statistically significant (P = 0.018) enhancement was found in the echogenicity of the total perivascular space (adventitial region and perivascular vessels), as indicated by an increase in grey level intensity from 8.33 ± 0.80 (before) to 10.11 ± 0.88 (after microbubble injection). A significant enhancement of the 11 selected ROI (perivascular structures) was also recorded after the injection of microbubbles (from 7.92 ± 2.14 to 14.03 ± 2.44; P = 0.008). 4We believe that the detection of perivascular structures with contrast-enhanced intracoronary ultrasonography combined with proper image processing may reinforce our future efforts in the detection of vasa vasorum, an active participant in the creation of acute coronary events. [source]

CYTIDINE 5,-DIPHOSPHOCHOLINE RESTORES BLOOD FLOW OF SUPERIOR MESENTERIC AND RENAL ARTERIES AND PROLONGS SURVIVAL TIME IN HAEMORRHAGED ANAESTHETIZED RATS

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2006
M Sertac Yilmaz
SUMMARY 1The aim of the present study was to investigate the effect of the intracerebroventricular (i.c.v.) or intravenous (i.v.) administration of cytidine 5¢-diphosphocholine (CDP-choline) on superior mesenteric artery (SMA) and renal artery (RA) blood flow, along with the cardiovascular parameters and survival time of anaesthetized rats under conditions of haemorrhagic shock. 2Rats were anaesthetized with urethane (1.25 g/kg, i.p.) and acute haemorrhage was mimicked by the withdrawal of a total volume of 2,2.1 mL blood/100 g bodyweight over a period of 20 min. The CDP-choline was injected i.c.v. (1.0, 1.5 and 2.0 mmol) or i.v. (250 mg/kg) after the end of haemorrhage. Blood pressure, heart rate, SMA and RA flow values and the survival time of rats were recorded. Changes in blood flow were estimated by laser-Doppler flowmetry. 3The haemorrhage procedure decreased the blood pressures of rats by 60% and limited their survival time to 22 ± 2 min. Both SMA and RA flow decreased to approximately 25% of initial values at the end of the haemorrhage procedure. 4The i.c.v. administration of CDP-choline (1.0, 1.5 and 2.0 mmol) increased blood pressure and partially reversed the hypotension in a dose- and time-dependent manner. At 1.5 and 2.0 mmol, i.c.v., CDP-choline completely restored the decreased flow of the RA and transiently reversed hypoperfusion of the SMA. It also produced an almost fourfold increase in the survival time of rats. 5The i.v. administration of CDP-choline (250 mg/kg) also completely, but transiently, restored SMA and RA flow, whereas it increased blood pressure by only 40% compared with control values. The survival time of rats in the i.v. CDP-choline group was doubled that of control. 6These results indicate that both centrally and peripherally injected CDP-choline can restore SMA and RA flow, together with a partial reversal of hypotension and an increase in the survival time of rats. [source]

Effect of Chronic Sustained-Release Dipyridamole on Myocardial Blood Flow and Left Ventricular Function in Patients With Ischemic Cardiomyopathy

CONGESTIVE HEART FAILURE, Issue 3 2007
Mateen Akhtar MD
Dipyridamole increases adenosine levels and augments coronary collateralization in patients with coronary ischemia. This pilot study tested whether a 6-month course of sustained-release dipyridamole/aspirin improves coronary flow reserve and left ventricular systolic function in patients with ischemic cardiomyopathy. Six outpatients with coronary artery disease and left ventricular ejection fraction (LVEF) <40% were treated with sustained-release dipyridamole 200 mg/aspirin 25 mg twice daily for 6 months. Myocardial function and perfusion, including coronary sinus flow at rest and during intravenous dipyridamole-induced hyperemia, were measured using velocity-encoded cine magnetic resonance stress perfusion studies at baseline, 3 months, and 6 months. There was no change in heart failure or angina class at 6 months. LVEF increased by 39%±64% (31.0%±13.3% at baseline vs 38.3%±10.7% at 6 months; P=.01), hyperemic coronary sinus flow increased more than 2-fold (219.6±121.3 mL/min vs 509.4±349.3 mL/min; P=.01), and stress-induced relative myocardial perfusion increased by 35%±13% (9.4%±3.4% vs 13.9%±8.5%; P=.004). Sustained-release dipyridamole improved hyperemic myocardial blood flow and left ventricular systolic function in patients with ischemic cardiomyopathy. [source]

Dynamic Variations of Local Cerebral Blood Flow in Maximal Electroshock Seizures in the Rat

EPILEPSIA, Issue 10 2002
Véronique André
Summary: ,Purpose: Measurement of cerebral blood flow is routinely used to locate the areas involved in generation and spread of seizures in epilepsy patients. Because the nature of the hyperperfused regions varies with the timing of injection of tracer, in this study, we used a rat model of maximal electroshock seizures to follow up the time-dependent changes in the distribution of seizure-induced cerebral blood flow (CBF) changes. Methods: CBF was measured by the quantitative autoradiographic [14C]iodoantipyrine technique over a 30-s duration. The tracer was injected either at 15 s before seizure induction, simultaneous with the application of the electroshock (tonic phase), at the onset of the clonic phase, or at 3 and 6 min after the seizure (postictal phase). Results: Rates of CBF underwent dynamic changes during the different phases of seizure activity and largely increased over control levels (,400%) in the 45 regions studied during all phases of the seizure (first 3 times). CBF remained higher than control levels in 35 and 15 areas at 3 and 6 min after the seizure, respectively. Conclusions: The distribution of maximal CBF increases showed a good correlation with their known involvement in the circuits underlying the clinical expression of the different types of seizure activity, tonic versus clonic. [source]

Changes in Cerebral Blood Flow During and After 48 H of Both Isocapnic and Poikilocapnic Hypoxia in Humans

EXPERIMENTAL PHYSIOLOGY, Issue 5 2002
Marc J. Poulin
During acclimatization to the hypoxia of altitude, the cerebral circulation is exposed to arterial hypoxia and hypocapnia, two stimuli with opposing influences on cerebral blood flow (CBF). In order to understand the resultant changes in CBF, this study examined the responses of CBF during a period of constant mild hypoxia both with and without concomitant regulation of arterial PCO2. Nine subjects were each exposed to two protocols in a purpose-built chamber: (1) 48 h of isocapnic hypoxia (Protocol I), where end-tidal PO2 (PET,O2) was held at 60 Torr and end-tidal PCO2 (PET,CO2) at the subject's resting value prior to experimentation; and (2) 48 h of poikilocapnic hypoxia (Protocol P), where PET,O2 was held at 60 Torr and PET,CO2 was uncontrolled. Transcranial Doppler ultrasound was used to assess CBF. At 24 h intervals during and after the hypoxic exposure CBF was measured and the sensitivity of CBF to acute variations in PO2 and PCO2 was determined. During Protocol P, PET,CO2 decreased by 13% (P < 0.001) and CBF decreased by 6% (P < 0.05), whereas during Protocol I, PET,CO2 and CBF remained unchanged. The sensitivity of CBF to acute variations in PO2 and PCO2 increased by 103% (P < 0.001) and 28% (P < 0.01), respectively, over the 48 h period of hypoxia. These changes did not differ between protocols. In conclusion, CBF decreases during mild poikilocapnic hypoxia, indicating that there is a predominant effect on CBF of the associated arterial hypocapnia. This fall occurs despite increases in the sensitivity of CBF to acute variations in PO2/PCO2 arising directly from the hypoxic exposure. [source]

The Effect of Progesterone on Coronary Blood Flow in Anaesthetized Pigs

EXPERIMENTAL PHYSIOLOGY, Issue 1 2001
C. Molinari
The present study was designed to investigate the effect of progesterone on the coronary circulation and to determine the mechanisms involved. In pigs anaesthetized with sodium pentobarbitone, changes in left circumflex or anterior descending coronary blood flow caused by intravenous infusion of progesterone at constant heart rate and arterial blood pressure were assessed using an electromagnetic flowmeter. In 14 pigs, infusion of 1 mg h,1 of progesterone caused an increase in coronary blood flow without affecting left ventricular dP/dtmax (rate of change of left ventricular systolic pressure) and filling pressures of the heart. In a further four pigs, this vasodilatory coronary effect was enhanced by graded increases in the dose of the hormone of between 1, 2 and 3 mg h,1. The mechanisms of the above response were studied in the 14 pigs by repeating the experiment after haemodynamic variables had returned to the control values observed before infusion. In six pigs, blockade of muscarinic cholinoceptors and adrenoceptors with atropine, propranolol and phentolamine did not affect the coronary vasodilatation caused by progesterone. In the remaining eight pigs, this response was abolished by intracoronary injection of N, -nitro-L-arginine methyl ester (L-NAME) even when performed after reversing the increase in arterial blood pressure and coronary vascular resistance caused by L-NAME with continuous intravenous infusion of papaverine. The present study showed that intravenous infusion of progesterone primarily caused coronary vasodilatation. The mechanism of this response was shown to involve the endothelial release of nitric oxide. [source]

Evaluation of Quantitative Portal Venous, Hepatic Arterial, and Total Hepatic Tissue Blood Flow Using Xenon CT in Alcoholic Liver Cirrhosis,Comparison With Liver Cirrhosis Related to Hepatitis C Virus and Nonalcoholic Steatohepatitis

ALCOHOLISM, Issue 2010
Hideaki Takahashi
Background/Aims:, Xenon computed tomography (Xe-CT) is a noninvasive method of quantifying and visualizing tissue blood flow (TBF). For the liver, Xe-CT allows separate measurement of hepatic arterial and portal venous TBF. The present study evaluated the usefulness of Xe-CT as a noninvasive diagnostic procedure for measuring hepatic TBF in alcoholic liver cirrhosis (AL-LC), compared with liver cirrhosis related to nonalcoholic steatohepatitis (NASH), (NASH-LC), and hepatitis C virus (HCV), (C-LC). Methods:, Xe-CT was performed on 22 patients with AL-LC, 7 patients with NASH-LC, and 24 patients with C-LC. Severity of LC was classified according to Child-Pugh classification. Correlations between hepatic TBF, Child-Pugh classification, and indocyanin green retention (ICG) rate after 15 minutes (ICG15R) were examined. Correlations of hepatic TBF in Child-Pugh class A to AL-LC, NASH-LC, and C-LC were also examined. Results:, Portal venous TBF (PVTBF) displayed a significant negative correlation with Child-Pugh score and ICG15R (r = ,0.432, p < 0.01, r = ,0.442, p < 0.01, respectively). Moreover, ICG15R displayed a significant positive correlation with Child-Pugh score (r = 0.661, p < 0.001). Meanwhile, mean PVTBF and total hepatic TBF (THTBF) was significantly lower in AL-LC than in C-LC (p < 0.05). Mean PVTBF was significantly lower in Child-Pugh class A to AL-LC and NASH-LC than in that to C-LC (p < 0.05). Similarly, mean THTBF was significantly lower in Child-Pugh class A to NASH-LC than in that to C-LC (p < 0.05). Conclusions:, Measurement of hepatic TBF using Xe-CT is useful as a noninvasive, objective method of assessing the state of the liver in chronic liver disease. [source]

Reduced Nerve Blood Flow In Diabetic Rats Is A Reflection Of Hindlimb Muscle Wasting

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000
Dr Tomlinson
We examined the influence of muscle wasting, as a result of streptozotocin-induced diabetes, on sciatic nerve laser Doppler flux (SNLDF), as an index of nerve blood flow, and conduction velocity (NCV). We compared dietary-restricted weight-reduced non-diabetic rats with controls and with diabetic rats and we studied the effects of clenbuterol, an anabolic ,-adrenoceptor agonist, in control and diabetic rats. Dietary restriction reduced the weights of hindlimb muscles,extensor digitorum longus, soleus and gastrocnemius,half as much as did streptozotocin-diabetes and clenbuterol increased muscle weights in control and diabetic rats. This gave a hierarchy of muscle weights in the order,clenbuterol-controls, untreated controls, weight-reduced non-diabetics, clenbuterol-diabetics and untreated diabetics. Diabetes without treatment reduced SNLDF by 51% (p < 0.01); dietary restriction by 25% (p < 0.01) and there were proportional increases associated with clenbuterol treatment. Combined muscle weights regressed closely with SNLDF (r2=0.69; p < 0.001) and, when the latter was expressed relative to muscle weights, a similar value was obtained for all five groups,there were no significant differences. Thus, sciatic nerve blood flow is closely related to hindlimb muscle weight and the effect of diabetes on nerve blood flow may be secondary to muscle wasting. Sciatic/tibialis motor and sensory conduction velocities were also reduced by muscle wasting in the dietary restricted group of non-diabetic rats, but, unlike nerve Doppler flux, it was unaffected by clenbuterol. [source]

RBC Aggregation: More Important than RBC Adhesion to Endothelial Cells as a Determinant of In Vivo Blood Flow in Health and Disease

MICROCIRCULATION, Issue 7 2008
OGUZ K. BASKURT
ABSTRACT Although the shear-dependent and reversible phenomenon of red blood cell (RBC) aggregation has been studied for decades, its role as a determinant of in vivo blood flow in both health and disease has not yet been fully documented. In this brief review, we present compelling arguments, supported by literature evidence, that in vivo flow dynamics are more affected by RBC aggregation than by RBC adhesion to endothelial cells (ECs). A companion article (i.e., a "counter-point") published in this issue of the journal argues that in disease states, RBC-EC adhesion is the more important determinant. [source]

Regulation of Muscle Blood Flow in Obesity

MICROCIRCULATION, Issue 4-5 2007
Benjamin L. Hodnett
ABSTRACT Obesity has been shown to impair muscle blood flow in humans. Vasodilatory control mechanisms such as metabolic control, myogenic mechanisms, conducted vasodilation, and release of endothelium-derived factors may be impaired in obesity due to insulin resistance, hyperglycemia, dyslipidemia, inflammation, oxidative stress, and endothelial dysfunction. The physiological importance of these blood flow control mechanisms has predominately been determined during the increase in blood flow (functional hyperemia) that occurs in response to the increased metabolism associated with exercise. This review examines the mechanisms by which functional hyperemia may be impaired in obesity and indicates areas where further studies are needed. The most extensively studied area of obesity-induced changes in muscle blood flow has been the role of endothelium-derived mediators during resting blood flow and exercise-induced hyperemia. Elevations in oxidative stress alter endothelium-derived factors, resulting in impaired vasodilatory responses. Alterations in metabolic and conducted vasodilatory regulation of blood flow have not been extensively studied in obesity, providing a potential area of research. [source]

Blood Flow in Snake Infrared Organs: Response-Induced Changes in Individual Vessels

MICROCIRCULATION, Issue 2 2007
RICHARD C. GORIS
ABSTRACT Objective: In the past the microkinetics of blood flow in the infrared pit organs of pit vipers has been studied with Doppler flowmetry using various infrared stimuli such as a human hand or soldering iron at various distances, lasers of various wavelengths, etc. Quick-acting variations in blood flow were recorded, and interpreted as a cooling mechanism for avoiding afterimage in the infrared receptors. However, the Doppler measurements provided only the summation of blood flow in a number of vessels covered by the sensing probe, but did not give data on flow in individual vessels. Methods: In the present work the authors introduced into the bloodstream of Gloydius and Trimeresurus pit vipers fluorescent microspheres labeled with fluorescein isothiocyanate (FITC) contained in a solution of FITC-dextran in physiological saline. They observed the passage of the microspheres through individual pit organ vessels with a fluorescent microscope to which was attached a high-speed video camera and image intensifier. Output of the camera was recorded before, during, and after stimulus with a 810-nm diode laser. Recording was done at 250 frames/s on high-speed video apparatus and downloaded to a hard disk. Disk files were loaded into proprietary software and particles were tracked and average velocities calculated. The data were then tested for significance by ANOVA with post hoc tests. Results: A significant (p < .05) increase in blood velocity was found at the focal point of the stimulus laser, but not anywhere removed from this point. Proximal severing of the pit sensory nerves caused degeneration of the pit receptor terminals and abolished stimulus-induced blood flow changes, but did not affect normal blood flow. Conclusions: The authors conclude that the receptors themselves are directly and locally controlling the smooth muscle elements of the blood vessels, in response to heating of the receptors by infrared radiation. They speculate that the heavy vascularization constitutes a cooling system for the radiation-encoding receptors, and further that the agent of control may be a volatile neuromediator such as nitric oxide. [source]

Influence of Glucose Control and Improvement of Insulin Resistance on Microvascular Blood Flow and Endothelial Function in Patients with Diabetes Mellitus Type 2

MICROCIRCULATION, Issue 7 2005
THOMAS FORST
ABSTRACT Objective: The study was performed to investigate the effect of improving metabolic control with pioglitazone in comparison to glimepiride on microvascular function in patients with diabetes mellitus type 2. Methods: A total of 179 patients were recruited and randomly assigned to one treatment group. Metabolic control (HbA1c), insulin resistance (HOMA index), and microvascular function (laser Doppler fluxmetry) were observed at baseline and after 3 and 6 months. Results: HbA1c improved in both treatment arms (pioglitazone: 7.52 ± 0.85% to 6.71 ± 0.89%, p < .0001; glimepiride: 7.44 ± 0.89% to 6.83 ± 0.85%, p < .0001). Insulin-resistance decreased significantly in the pioglitazone group (6.15 ± 4.05 to 3.85 ± 1.92, p < .0001) and remained unchanged in the glimepiride group. The microvascular response to heat significantly improved in both treatment groups (pioglitazone 48.5 [15.2; 91.8] to 88.8 [57.6; 124.1] arbitrary units [AU], p < .0001; glimepiride 53.7 [14.1; 91.9] to 87.9 [52.9, 131.0] AU, p < .0001, median [lower and upper quartile]). Endothelial function as measured with the acetylcholine response improved in the pioglitazone group (38.5 [22.2; 68.0] to 60.2 [36.9; 82.8], p = .0427) and remained unchanged in the glimepiride group. Conclusions: Improving metabolic control has beneficial effects in microvascular function in type 2 diabetic patients. Treatment of type 2 diabetic patients with pioglitazone exerts additional effects on endothelial function beyond metabolic control. [source]

Regulation of Blood Flow in the Microcirculation

MICROCIRCULATION, Issue 1 2005
STEVEN S. SEGAL
ABSTRACT The regulation of blood flow has rich history of investigation and is exemplified in exercising skeletal muscle by a concerted interaction between striated muscle fibers and their microvascular supply. This review considers blood flow control in light of the regulation of capillary perfusion by and among terminal arterioles, the distribution of blood flow in arteriolar networks according to metabolic and hemodynamic feedback from active muscle fibers, and the balance between peak muscle blood flow and arterial blood pressure by sympathetic nerve activity. As metabolic demand increases, the locus of regulating oxygen delivery to muscle fibers "ascends" from terminal arterioles, through intermediate distributing arterioles, and into the proximal arterioles and feed arteries, which govern total flow into a muscle. At multiple levels, venules are positioned to provide feedback to nearby arterioles regarding the metabolic state of the tissue through the convection and production of vasodilator stimuli. Electrical signals initiated on smooth muscle and endothelial cells can travel rapidly for millimeters through cell-to-cell conduction via gap junction channels, rapidly coordinating vasodilator responses that govern the distribution and magnitude of blood flow to active muscle fibers. Sympathetic constriction of proximal arterioles and feed arteries can restrict functional hyperemia while dilation prevails in distal arterioles to promote oxygen extraction. With vasomotor tone reflecting myogenic contraction of smooth muscle cells modulated by flow-induced vasodilator production by endothelium, the initiation of functional vasodilation and its modulation by shear stress and sympathetic innervation dictate how and where blood flow is distributed in microvascular networks. A remarkable ensemble of signaling pathways underlie the integration of smooth muscle and endothelial cell function in microvascular networks. These pathways are being defined with new insight as novel approaches are applied to understanding the cellular and molecular mechanisms of blood flow control. [source]

Coronary Blood Flow Produced by Muscle Contractions Induced by Intracardiac Electrical CPR during Ventricular Fibrillation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 2009
HAO WANG M.D.
It has been reported that transthoracic electrical cardiopulmonary resuscitation (ECPR) generates coronary perfusion pressures (CPP) similar to manual chest compressions (MCC). We hypothesized that intracardiac ECPR produces similar CPP. Methods: ECPR pulse train protocols were applied for 20 seconds in a porcine model following 10 seconds of ventricular fibrillation (VF), using a defibrillator housing electrode and a right ventricular coil (IC-ECPR). Each protocol consisted of 200-ms electrical pulse trains applied at a rate of 100 pulse trains/min. The protocols were grouped in skeletal-based versus cardiac-based stimulation measurements. CPP was recorded and compared to historical MCC values generated by a similar experimental design. CPP > 15 mm Hg at 30 seconds of VF following the application of an IC-ECPR protocol was defined as successful. Results: Mean CPP for all intracardiac ECPR pulse train protocols at 30 seconds of VF was 14.8 ± 3.8 mm Hg (n = 39). Mean CPP in seven successful skeletal-based IC-ECPR protocols was 19.4 ± 3.2 mm Hg, and mean CPP in 10 successful cardiac-based IC-ECPR protocols was 17.4 ± 2.1 mm Hg. Reported CPP for 15 MCC experiments at 30 seconds of VF was 22.9 ± 9.4 mm Hg (P = 0.35 compared to skeletal-based IC-ECPR, P = 0.08 compared to cardiac-based IC-ECPR). Conclusions: Intracardiac applied electrical CPR produced observable skeletal muscle contractions, measurable pressure pulses, and coronary perfusion pressures similar to MCC during a brief episode of untreated VF. [source]

Bimodal Oscillation Frequencies of Blood Flow in the Inflammatory Colon Microcirculation

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2009
Akira Tsuda
Abstract Rhythmic changes in blood flow direction have been described in the mucosal plexus of mice with acute colitis. In this report, we studied mice with acute colitis induced either by dextran sodium sulfate or by trinitrobenzenesulfonic acid. Both forms of colitis were associated with blood flow oscillations as documented by fluorescence intravital videomicroscopy. The complex oscillation patterns suggested more than one mechanism for these changes in blood flow. By tracking fluorescent nanoparticles in the inflamed mucosal plexus, we identified two forms of blood flow oscillations within the inflammatory mouse colon. Stable oscillations were associated with a base frequency of approximately 2 cycles/sec. Velocity measurements in the upstream and downstream vessel segments indicated that stable oscillations were the result of regional flow occlusion within the mucosal plexus. In contrast, metastable oscillations demonstrated a lower frequency (0.2,0.4 cycles/sec) and appeared to be the result of flow dynamics in vessels linked by the bridging mucosal vessels. These blood flow oscillations were not directly associated with cardiopulmonary movement. We conclude that both the stable and metasable oscillating patterns reflect flow adaptations to inflammatory changes in the mucosal plexus. Anat Rec, 2009. © 2008 Wiley-Liss, Inc. [source]

Bridging Mucosal Vessels Associated with Rhythmically Oscillating Blood Flow in Murine Colitis

THE ANATOMICAL RECORD : ADVANCES IN INTEGRATIVE ANATOMY AND EVOLUTIONARY BIOLOGY, Issue 1 2008
Aslihan Turhan
Abstract Oscillatory blood flow in the microcirculation is generally considered to be the result of cardiopulmonary influences or active vasomotion. In this report, we describe rhythmically oscillating blood flow in the bridging vessels of the mouse colon that appeared to be independent of known biological control mechanisms. Corrosion casting and scanning electron microscopy of the mouse colon demonstrated highly branched bridging vessels that connected the submucosal vessels with the mucosal plexus. Because of similar morphometric characteristics (19 ± 11 ,m vs. 28 ± 16 ,m), bridging arterioles and venules were distinguished by tracking fluorescent nanoparticles through the microcirculation using intravital fluorescence videomicroscopy. In control mice, the blood flow through the bridging vessels was typically continuous and unidirectional. In contrast, two models of chemically induced inflammation (trinitrobenzenesulfonic acid and dextran sodium sulfate) were associated with a twofold reduction in flow velocity and the prominence of rhythmically oscillating blood flow. The blood oscillation was characterized by tracking the bidirectional displacement of fluorescent nanoparticles. Space,time plots and particle tracking of the oscillating segments demonstrated an oscillation frequency between 0.2 and 5.1 cycles per second. Discrete Fourier transforms demonstrated a power spectrum composed of several base frequencies. These observations suggest that inflammation-inducible changes in blood flow patterns in the murine colon resulted in both reduced blood flow velocity and rhythmic oscillations within the bridging vessels of the mouse colon. Anat Rec, 291:74,82, 2007. © 2007 Wiley-Liss, Inc. [source]

ORIGINAL RESEARCH,ENDOCRINOLOGY: Pulse Pressure, an Index of Arterial Stiffness, Is Associated with Androgen Deficiency and Impaired Penile Blood Flow in Men with ED

THE JOURNAL OF SEXUAL MEDICINE, Issue 1 2009
Giovanni Corona MD
ABSTRACT Introduction., Pulse pressure (PP; i.e., the arithmetic difference between systolic and diastolic blood pressure) reflects arterial stiffness and has been suggested to be an independent cardiovascular risk factor. Aim., The aim of the present study is to asses the possible contribution of PP to arteriogenic erectile dysfunction (ED) and ED-associated hypogonadism. Methods., A consecutive series of 1,093 (mean age 52.1 ± 13.0 years) male patients with ED and without a previous history of hypertension or not taking any antihypertensive drugs were investigated. Main Outcome Measures., Several hormonal and biochemical parameters were studied, along with structured interview on erectile dysfunction (SIEDY), ANDROTEST structured interviews, and penile Doppler ultrasound. Results., Subjects with higher PP quartiles showed worse erectile function and higher prevalence of arteriogenic ED even after adjustment for confounding factors. Furthermore, sex hormone binding globulin-unbound testosterone levels declined as a function of PP quartiles. Accordingly, the prevalence of overt hypogonadism (calculated free testosterone < 180 pmol/L or free testosterone < 37 pmol/L) increased as a function of PP quartiles (17.% vs. 39.7%, and 30.8% vs. 58.6% for the first vs. fourth quartile, respectively, for calculated free testosterone and free testosterone; all P < 0.0001 for trend). This association was confirmed even after adjustment for confounders (Adjusted [Adj]) r = 0.090 and 0.095 for calculated free testosterone < 180 pmol/L and free testosterone < 37 pmol/L, respectively; all P < 0.05). Conclusions., PP is an easy method to estimate and quantify patient arterial stiffness. We demonstrated here for the first time that elevated PP is associated with arteriogenic ED and male hypogonadism. The calculation of PP should became more and more familiar in the clinical practice of health care professionals involved in sexual medicine. Corona G, Mannucci E, Lotti F, Fisher AD, Bandini E, Balercia G, Forti G, and Maggi M. Pulse pressure, an index of arterial stiffness, is associated with androgen deficiency and impaired penile blood flow in men with ED. J Sex Med 2009;6:285,293. [source]

RGS4 Controls Renal Blood Flow and Inhibits Cyclosporine-Mediated Nephrotoxicity

AMERICAN JOURNAL OF TRANSPLANTATION, Issue 2 2010
A. Siedlecki
Calcineurin inhibitors (CNI) are powerful immunomodulatory agents that produce marked renal dysfunction due in part to endothelin-1-mediated reductions in renal blood flow. Ligand-stimulated Gq protein signaling promotes the contraction of smooth muscle cells via phospholipase C,-mediated stimulation of cytosolic calcium release. RGS4 is a GTPase activating protein that promotes the deactivation of Gq and Gi family members. To investigate the role of G protein-mediated signaling in the pathogenesis of CNI-mediated renal injury, we used mice deficient for RGS4 (rgs4,/,). Compared to congenic wild type control animals, rgs4,/, mice were intolerant of the CNI, cyclosporine (CyA), rapidly developing fatal renal failure. Rgs4,/, mice exhibited markedly reduced renal blood flow after CyA treatment when compared to congenic wild type control mice as measured by magnetic resonance imaging (MRI). Hypoperfusion was reversed by coadministration of CyA with the endothelin antagonist, bosentan. The MAPK/ERK pathway was activated by cyclosporine administration and was inhibited by cotreatment with bosentan. These results show that endothelin-1-mediated Gq protein signaling plays a key role in the pathogenesis of vasoconstrictive renal injury and that RGS4 antagonizes the deleterious effects of excess endothelin receptor activation in the kidney. [source]

Cocaine and Ethanol: Combined Effects on Coronary Artery Blood Flow and Myocardial Function in Dogs

ACADEMIC EMERGENCY MEDICINE, Issue 7 2009
Lance D. Wilson MD
Abstract Objectives:, In combination, cocaine and ethanol are more cardiotoxic than is either substance alone. These substances together constitute a drug abuse combination that commonly results in fatality. Previously the authors have demonstrated that cardiotoxicity of cocaine and ethanol is in part due to synergistic myocardial-depressant effects. However, it remains unclear whether this myocardial depression is associated with concomitant adverse effects on coronary blood flow in relation to these substances. The aim of this study was to investigate combined effects of cocaine and ethanol on myocardial blood flow, in relation to indices of myocardial function. Methods:, Anesthetized dogs were instrumented for hemodynamic monitoring with Doppler flow probes placed on the circumflex and left anterior descending (LAD) coronary arteries. Dogs were randomized to three groups (each n = 6): ethanol (E, 1.5 g/kg followed by placebo), cocaine (C, placebo followed by cocaine, 7.5 mg/kg IV), or cocaine plus ethanol (C + E). All measurements were made at control, after placebo or ethanol, and then at fixed time intervals after cocaine or placebo bolus over 3 hours. Results:, In both the C + E and the C groups, circumflex blood flow (CBF) decreased by 71% (95% confidence interval [CI] = 56% to 85%) and 57% (95% CI = 43% to 72%, both p < 0.04 vs. baseline) immediately after cocaine bolus. This was associated with transient depression of cardiac output, myocardial contractile function, and rate-pressure product (RPP), all indices of myocardial oxygen demand. A subsequent rebound increase of coronary sinus blood flow (CSBF) of 56% (95% CI = 26% to 137%, p < 0.03) compared to baseline occurred only in the C group and was associated with increases of myocardial contractile function and RPP. In the C + E group, 2 hours after drug administration, there was a decrease in CSBF of 49% (95% CI = 32% to 67%; p < 0.01) compared to baseline, which was associated with concomitant numerical decreases of the indices of myocardial oxygen demand and accumulation of cocaethylene. Conclusions:, Acute decreases in myocardial flow secondary to cocaine, and cocaine and ethanol in combination, were similar and temporally associated with cocaine's direct myocardial-depressant effects. Rebound increases in myocardial function and blood flow due to cocaine were attenuated by ethanol. Delayed myocardial depression and decreases in myocardial blood flow were observed only with coadministration of cocaine and ethanol. [source]

The Influence of Cannulation Technique on Blood Flow to the Brain in Rats Undergoing Cardiopulmonary Bypass: A Cautionary "Tail"

ARTIFICIAL ORGANS, Issue 6 2010
Terence Gourlay
Abstract Recently, there has been an increase in the use of rat models of cardiopulmonary bypass (CPB) for research purposes. Much of this work has focused on cerebral injury associated with CPB. Many of these studies employ a peripheral cannulation approach, often utilizing the caudal artery and internal or external jugular vein. The aim of the present study was to establish whether there is any alteration in blood flow to the brain associated with the use of different cannulation routes. Twenty-four adult male Sprague Dawley rats were allocated to one of three study groups: Group 1,caudal artery return, Group 2,open-chest aortic return, and Group 3,nonbypass control group. Colored microspheres were injected into all animals at four time points (postinduction, initiation of bypass, midbypass, and end bypass). After the termination of each experiment, the brains were excised, the tissue was digested, the microspheres were harvested, and the global blood flow to the brain was assessed using the reference flow method. There was a significant reduction in blood flow to the brain between both bypass groups and the control group. Additionally, cerebral blood flow was significantly lower in the caudal return group than in the aortic return group. There is a significant drop in blood flow to the brain associated with the initiation and continuation of CPB when compared to non-CPB controls. These results also confirm a considerable cerebral hypoperfusion associated with the peripheral cannulation technique, and suggest that peripheral bypass may exaggerate the influence CPB has on cerebral injury. This technique must therefore be employed with caution. [source]

Increased Cerebral Blood Flow And Cardiac Output Following Cerebral Arterial Air Embolism In Sheep

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 11 2001
David J Williams
SUMMARY 1. The effects of cerebral arterial gas embolism on cerebral blood flow and systemic cardiovascular parameters were assessed in anaesthetized sheep. 2. Six sheep received a 2.5 mL injection of air simultaneously into each common carotid artery over 5 s. Mean arterial blood pressure, heart rate, end-tidal carbon dioxide and an ultrasonic Doppler index of cerebral blood flow were monitored continuously. Cardiac output was determined by periodic thermodilution. 3. Intracarotid injection of air produced an immediate drop in mean cerebral blood flow. This drop was transient and mean cerebral blood flow subsequently increased to 151% before declining slowly to baseline. Coincident with the increased cerebral blood flow was a sustained increase in mean cardiac output to 161% of baseline. Mean arterial blood pressure, heart rate and end-tidal carbon dioxide were not significantly altered by the intracarotid injection of air. 4. The increased cardiac output is a pathological response to impact of arterial air bubbles on the brain, possibly the brainstem. The increased cerebral blood flow is probably the result of the increased cardiac output and dilation of cerebral resistance vessels caused by the passage of air bubbles. [source]

Neural Regulation Of Renal Blood Flow: A Re-Examination

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 12 2000
Simon C Malpas
SUMMARY 1. The importance of renal sympathetic nerve activity (RSNA) in the regulation of renal function is well established. However, it is less clear how the renal vasculature responds to the different mean levels and patterns of RSNA. While many studies have indicated that small to moderate changes in RSNA preferentially regulate renin secretion or sodium excretion and only large changes in RSNA regulate renal blood flow (RBF), other experimental evidence suggests that small changes in RSNA can influence RBF 2. When RSNA has been directly measured in conjunction with RBF, it appears that a range of afferent stimuli can induce reflex changes in RBF. However, many studies in a variety of species have measured RBF only during stimuli designed to reflexly increase or decrease sympathetic activity, but have not recorded RSNA. While this approach can be informative, it is not definitive because the ability of the vasculature to respond to RSNA may, in part, reflect the resting level of RSNA and, therefore, the vasoconstrictive state of the vasculature under the control conditions. 3. Further understanding of the control of RBF by RSNA has come from studies that have analysed the underlying rhythms in sympathetic nerve activity and their effect on the cardiovascular system. These studies show that the frequency,response characteristic of the renal vasculature is such that higher frequency oscillations in RSNA (above 0.6 Hz) contribute to setting the mean level of RBF. In comparison, lower frequency oscillations in RSNA can induce cyclic vasoconstriction and dilation in the renal vasculature, thus inducing oscillations in RBF. 4. In summary, the present review discusses the neural control of RBF, summarizing evidence in support of the hypothesis that RBF is under the influence of RSNA across the full range of RSNA. [source]

Higher arterial stiffness, greater peripheral vascular resistance and lower blood flow in lower-leg arteries are associated with long-term hyperglycaemia in type 2 diabetic patients with normal ankle-brachial index

DIABETES/METABOLISM: RESEARCH AND REVIEWS, Issue 4 2009
Eiji Suzuki
Abstract Background Higher arterial stiffness and greater peripheral vascular resistance reduce blood flow in lower-leg arteries and contribute to the development of ischaemic limb in diabetic patients even without peripheral artery occlusive disease. The aim of this study was to clarify whether these vascular parameters are associated with long-term hyperglycaemia in diabetic patients. Methods We examined 45 type 2 diabetic patients and 38 age-matched nondiabetic subjects without peripheral artery occlusive disease assessed by ankle-brachial index consecutively admitted to our hospital, and followed them over a 3-year period (3.7 ± 0.7 years) with no vasodilative medication. Blood flow and resistive index, a measure of peripheral vascular resistance, at the popliteal artery were evaluated using gated two-dimensional cine-mode phase-contrast magnetic resonance imaging. Brachial-ankle pulse wave velocity was measured to assess arterial stiffness. Results At baseline, consistent with our previous report, diabetic patients showed higher brachial-ankle pulse wave velocity (p < 0.0001) and resistive index (p < 0.0001) and lower flow volume (p = 0.0044) than those of nondiabetic subjects. Stepwise multiple regression analysis revealed that duration of diabetes, mean HbA1c during the study, use of renin-angiotensin system inhibitors and change per year in resistive index were identified as significant independent variables predicting change per year in blood flow (r2 = 0.733, p < 0.0001) in diabetic patients. Mean HbA1c during the study was positively correlated with changes per year in brachial-ankle pulse wave velocity (p = 0.00007) and resistive index (p = 0.0014) and was negatively correlated with that in blood flow (p < 0.0001) in diabetic patients. Conclusions Long-term hyperglycaemia is a major cause of impaired peripheral circulation in lower-leg arteries in diabetic patients without peripheral artery occlusive disease. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Beta-2-Microglobulin in nocturnal hemodialysis , A comparative study in low and high flux dialysers

HEMODIALYSIS INTERNATIONAL, Issue 1 2005
A.B. Reid
In end-stage renal failure, impaired renal catabolism leads to retention of beta 2 microglobulin (ß2M), identified as the major constituent of hemodialysis (HD) related amyloidosis. It has been previously shown that, while using a high flux (HF) HD membrane, nocturnal hemodialysis (NHD) with its increased time and frequency provides a much higher clearance of ß2M compared to conventional HD. We compared serum ß2M levels between low flux (LF) and HF in a group of 9 NHD patients who dialyse 8 hours 6 nights/week. Fresenius polysulfone LF membrane size F6-F8 HPS dialyser were used for the first 15 months (mth) of NHD (SA 1.3,1.8 m2). Subsequently, polysulfone HF FX80 dialyzer were used (SA 1.8 m2). Blood flow and dialysate flow rates were unchanged throughout the study. ß2M levels were measured at 6, 12, 15 mth on LF and at 6, 12 mth on HF. Albumin, homocysteine (Hcy), and phosphate (Phos) levels were also recorded at these times. ß2M levels trended upwards during the 15 mth on LF (36.6 ± 10.57 at 6 mth vs 47.1 ± 11.7 at 15 mth). On introduction of HF, there was a significant fall in ß2M at 6 mth to 12.4 ± 3.5 (p < 0.003), while ß2M levels were unchanged at 12 mth of HF. A downward trend in Hcy levels with the use of HF was noted (12.9 ± 2.9 at 0 mth Vs 11.1 ± 3.7 at 12 mth). Plasma albumin and Phos levels remained unchanged as did the use of Phos supplementation. Levels of ß2M continued to rise on NHD with LF, indicating inadequate clearance. With the introduction of HF there was a significant fall in ß2M levels consistent with improved clearance. The implications of this are that ß2M clearance may be time and frequency dependent only if dialyser membrane flux is adequate. [source]

Color doppler imaging in the sonohysterographic diagnosis of residual trophoblastic tissue

JOURNAL OF CLINICAL ULTRASOUND, Issue 4 2002
Yaron Zalel MD
Abstract Purpose The purpose of this study was to evaluate the role of color Doppler imaging during sonohysterography in the diagnosis of residual trophoblastic tissue. Methods This prospective cohort study involved 25 consecutive women with clinical and sonographic signs of an echogenic intrauterine mass who were referred to the sonography unit of our institution for evaluation. All women underwent saline infusion sonohysterography with color Doppler sonographic evaluation. An operative hysteroscopy with histologic examination was performed in 17 cases. Results Thirteen women (group A) had sonohysterographic features suggestive of residual tropho- blastic tissue (ie, an echogenic intrauterine lesion not detached from the uterine wall after introduction of saline). The initial diagnosis was confirmed by histologic analysis in all cases. Blood flow was detected within the intrauterine mass in 6 (46%) of these 13 women; the resistance indices were low in all 6 cases (mean ± standard error, 0.38 ± 0.01). Twelve women (group B) had sonohysterographic findings negative for retained tissue, and no blood flow was detected within any of the intrauterine masses in this group (p < 0.05). Conclusions Our results confirm the potential role of color Doppler sonography in the initial diagnosis of residual trophoblastic tissue. The detection of color Doppler signals, especially with low-resistance flow, within an intrauterine lesion should increase the confidence of the sonologist in the diagnosis of residual trophoblastic tissue. © 2002 Wiley Periodicals, Inc. J Clin Ultrasound 30: 222,225, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI: 10.1002/jcu.10059 [source]

Influence of gum-chewing on the haemodynamics in female masseter muscle

JOURNAL OF ORAL REHABILITATION, Issue 4 2009
N. ABE
Summary, Blood flow in active skeletal muscles provides energy substrate, oxygen and reduction of excessive heat and metabolic by-products. Although cyclic jaw motions such as those during mastication and speech articulation are the primitive oro-facial functions, possible effects of the cyclic muscle contractions on the intramuscular haemodynamics of the jaw muscles remains scarcely known. We investigated the masseteric haemodynamics during and after gum-chewing. Ten healthy female adults participated in the study. Electromyography, kinetics of masseter muscle oxygenation, electrocardiogram and blood pressure were recorded simultaneously. The subjects were asked to perform gum-chewing and cyclic jaw motion without gum bolus (empty-chewing task). The haemodynamics parameters were compared between the two experimental conditions. During gum-chewing task, deoxygenated haemoglobin and sympathetic nerve activity increased, while tissue blood oxygen saturation decreased. Blood pressure and parasympathetic nerve activity did not change. The overall behaviour of haemodynamic parameters during empty-chewing task was similar to that observed during gum-chewing task. However, the latency periods from the end of chewing until significant changes in the haemodynamic parameters were notably shorter (P < 0·05) in gum-chewing task as compared with those associated with empty-chewing task. The duration of the changes was shorter with empty-chewing than with gum-chewing. Fluctuations in masseter muscle haemodynamics associated with chewing jaw movement differed depending on the level of muscle contraction during movement. The differences became statistically significant immediately after the commencement of chewing and after the cessation movement. During the chewing movement, automatic nerve activities increased in response to the level of muscle contraction during movement. [source]

Morphological and molecular changes in denture-supporting tissues under persistent mechanical stress in rats

JOURNAL OF ORAL REHABILITATION, Issue 12 2008
M. TSURUOKA
Summary, The purpose of this study was to determine the effects of mechanical compression on the palatal mucosa using an experimental palatal base. The palatal base was either pressed onto (stress group) or not pressed onto (fit group) rat palatal mucosa. Blood flow was measured and the animals were sacrificed 6,72 h later for analysis. The expression of heat shock protein 70 (HSP70), vascular endothelial growth factor (VEGF) and proliferation cell nuclear antigen (PCNA) was characterized by immunohistochemical staining. For morphometric analysis, connective tissues were divided into bone side and epithelial side tissues. The ratio of PCNA-positive cells (PCNA score) was calculated, and the expressions of mRNA encoding HSP70 and VEGF was evaluated. Whereas blood flow in the stress group showed ischaemia, none was found in the fit group. Proliferation cell nuclear antigen scores on the bone side were higher than on the epithelial side in the stress group (P < 0·05). Heat shock protein 70- and VEGF-positive cells were observed under compression conditions, particularly in the periosteum. In the stress group, the expressions of mRNA encoding HSP70 and VEGF were highest at 12 h (P < 0·05). These results suggest that mechanical compression of the palatal plate induces ischaemia, and that cells in the underlying denture-supporting tissue, which includes the periosteum, synthesize HSP70 and VEGF to maintain homeostasis under these conditions. [source]

Measurement of bone blood flow using the hydrogen washout technique,part II: Validation by comparison to microsphere entrapment

JOURNAL OF ORTHOPAEDIC RESEARCH, Issue 6 2008
Mikko Larsen
Abstract Accurate and reproducible measurement of bone blood flow has important clinical and experimental applications. Hydrogen washout is simple, safe, and widely used, but its use in bone tissue has not been validated. To this end, we have compared cortical bone blood flow measurements obtained by radioactive-labeled microsphere entrapment with those from hydrogen washout. Blood flow was measured in tibial cortical bone of 12 New Zealand White rabbits by radioactive microsphere entrapment and by hydrogen washout. Besides a control group (n,=,6), four animals were treated with systemic epinephrine (0.8 µg/kg/min) (group 2) and two with nitroprusside (100 µg/kg/min) (group 3). Furthermore, nine femora from seven rats were isolated on their vascular pedicles and repeated bone blood flow measurements were made at each location with the hydrogen washout method to confirm reproducibility of blood flow determinations by hydrogen washout. An average flow of 2.3,±,2.0 mL/min/100 g was obtained with the microsphere method and 2.0,±,0.5 mL/min/100 g with the hydrogen washout method. There was a significant correlation and agreement: R2,=,0.97 (p,<,0.01). No consistent flow variations were found with systemic vasoactive drug administration. Hydrogen washout provided reproducible results and showed high sensitivity to flow changes. Hydrogen washout is both sensitive and reproducible in measuring bone blood flow. Results agree well with flow values obtained by labeled microsphere entrapment. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:746,752, 2008 [source]

The acute effects of smokeless tobacco (snuff) on gingival blood flow in man

JOURNAL OF PERIODONTAL RESEARCH, Issue 4 2001
Antonios Mavropoulos
Snuff-induced blood flow responses in the gingiva were evaluated in 22 healthy casual consumers of tobacco. Laser Doppler flowmetry (LDF) was used to measure blood flow simultaneously and continuously on two gingival sites (buccal aspect of the papillae between the upper lateral incisors and canines). In addition, measurements of skin blood flow in the forehead and palmar side of the left thumb were performed. Arterial blood pressure (BP) and heart rate (HR) were also recorded. Unilateral application of commercial snuff (500 mg, 1%) caused a marked and rapid increase in gingival blood flow (GBF) on the exposed side (p<0.001). Blood flow increased also in the contralateral gingiva and forehead skin (p<0.05). Skin blood flow in the thumb showed an insignificant decrease. BP and HR increased. Vascular conductance increased significantly in the snuff-exposed gingiva but not in the contralateral gingiva or the forehead. Vascular conductance was largely unaffected in the thumb. It is concluded that acute application of snuff, besides giving rise to typical changes in BP and HR, increases GBF in and around the exposed area, probably through activation of sensory nerves and the subsequent release of vasodilatory peptides from their peripheral endings. Blood flow in unexposed gingival and forehead skin may increase probably due to humoral or nervously mediated mechanisms. However, a passive pressure-induced hyperaemia in the unexposed gingiva and forehead skin can not be excluded. [source]