CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 8 2007
Fung Ping Leung
SUMMARY 1Oestrogen deficiency causes progressive reduction in endothelial function. Despite the benefits of hormone-replacement therapy (HRT) evident in earlier epidemiological studies, recent randomized trials of HRT for the prevention of heart disease found no overall benefit. Instead, HRT users had higher incidences of stroke and heart attack. Most women discontinue HRT because of its many side-effects and/or the increased risk of breast and uterine cancer. This has contributed to the development of selective oestrogen receptor modulators (SERMs), such as tamoxifen and raloxifene, as alternative oestrogenic agents. 2A SERM is a molecule that binds with high affinity to oestrogen receptors but has tissue-specific effects distinct from oestrogen, acting as an oestrogen agonist in some tissues and as an antagonist in others. Clinical and animal studies suggest multiple cardiovascular effects of SERMs. For example, raloxifene lowers serum levels of cholesterol and homocysteine, attenuates oxidation of low-density lipoprotein, inhibits endothelial,leucocyte interaction, improves endothelial function and reduces vascular smooth muscle tone. 3Available evidence suggests that raloxifene and tamoxifen are capable of acting directly on both endothelial cells and the underlying vascular smooth muscle cells and cause a multitude of favourable modifications of the vascular wall, which jointly contribute to improved local blood flow. The outcome of the Raloxifene Use for the Heart (RUTH) trial will determine whether raloxifene, currently approved for the treatment of post-menopausal osteoporosis, could substitute for HRT in alleviating cardiovascular symptoms in post-menopausal women. [source]

IMPACT OF OBESITY AND INSULIN RESISTANCE ON VASOMOTOR TONE: NITRIC OXIDE AND BEYOND

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2006
David W Stepp
SUMMARY 1Obesity is rapidly increasing in Western populations, driving a parallel increase in hypertension, diabetes and vascular disease. Prior to the development of overt diabetes or hypertension, obese patients spend years in a state of progressive insulin resistance and metabolic disease. Mounting evidence suggests that this insulin-resistant state has deleterious effects on the control of blood flow, thus placing organ systems at a higher risk for end-organ damage and increasing cardiovascular mortality. 2The purpose of the present review is to examine the current literature on the effects of obesity and insulin resistance on the acute control of vascular tone. Effects on nitric oxide (NO)-mediated control of vascular tone are particularly examined with regard to proximal causes and distal mechanisms of the impaired NO-mediation of vasodilation. 3Finally, novel pathways of impaired control of perfusion are summarized from the recent literature to identify new avenues of exploring impaired vascular function in patients with metabolic disease. [source]

Possible Contribution of Central Gamma-Aminobutyric Acid Receptors to Resting Vascular Tone in Freely Moving Rats

EXPERIMENTAL PHYSIOLOGY, Issue 5 2000
Yumi Takemoto
Previous studies have shown that central administration of GABA (gamma-aminobutyric acid), an inhibitory neurotransmitter, preferentially reduces hindquarters and carotid vascular resistances but not renal and coeliac vascular resistances in conscious rats. This study tested the hypothesis that these preferential actions of central GABA receptors are related to differences between vessels in resting autonomic vascular tone in freely moving rats. Rats were chronically implanted with intracisternal cannulas and/or electromagnetic probes to measure regional blood flows. In response to GABA administration, the changes in vascular resistance (arterial blood pressure/regional blood flow) of the hindquarters (n = 23) and carotid (n = 12) vascular beds were significantly and negatively correlated with basal vascular resistance. No such relationship was found for the renal (n = 21), coeliac (n = 13) and superior mesenteric (n = 23) vascular beds. This finding indicates that the responsiveness to GABA of brainstem pathways controlling the hindquarters and carotid vascular beds co-varies with resting resistance in hindquarters and carotid vessels. A similar analysis was performed, correlating the ongoing vascular resistance of each vessel with its response to ganglionic blockade by chlorisondamine. In this case, a significant negative correlation was also found for the hindquarters (n = 26) and carotid (n = 15) vascular beds, but not for the coeliac (n = 17) or superior mesenteric (n = 19) vessels. Together, these findings suggest that central GABA receptors accessible from the cisterna magna preferentially affect two vascular beds which, in the freely moving rat, show resting autonomic vascular tone. [source]

Vagal Tone: Myths and Realities

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 8 2005
PHYLLIS K. STEIN Ph.D.
No abstract is available for this article. [source]

Role of Autonomic Tone in the Initiation and Termination of Paroxysmal Atrial Fibrillation in Patients Without Structural Heart Disease

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2003
Takeshi Tomita M.D.
Introduction: Previous studies have suggested that paroxysmal atrial fibrillation (PAF) of vagal origin often occurs at night and PAF of sympathetic origin occurs during the daytime; however, autonomic tone after spontaneous termination of PAF has not been determined. The aim of this study was to evaluate by heart rate variability (HRV) analysis the relationship between the time of PAF onset and autonomic tone before and after PAF. Methods and Results: Twenty-three patients (65 ± 2years) who underwent 24-hour ambulatory monitoring, had one or more episodes of PAF (>30 min), and had maintained normal sinus rhythm for >60 min before/after PAF were enrolled in this study. Mean duration of PAF was6.2 ± 1.2hours. HRV parameters were analyzed in a 10-minutes section at 60 minutes, 20 minutes, and immediately before the onset of PAF and after its termination. PAF began at night in 14 patients (group N) and during the daytime in 9 patients (group D). In group N, the high-frequency (HF) component and low-frequency (LF) component showed a significant decrease after PAF; PAF was preceded by a gradual increase in HF and LF. Changes in the LF/HF ratio, however, did not occur before or after PAF. Conversely, group D showed a significant increase in the LF/HF ratio before PAF and a decrease in LF and the LF/HF ratio after PAF, but no changes in HF. These changes in HRV parameters were not influenced by the duration or termination time of PAF. Conclusion: This study suggests that the autonomic nervous system plays an important role in both the initiation and termination of PAF. Furthermore, the time of PAF onset influences the autonomic tone at the initiation and termination of PAF. (J Cardiovasc Electrophysiol, Vol. 14, pp. 559-564, June 2003) [source]

Fluctuation in Autonomic Tone is a Major Determinant of Sustained Atrial Arrhythmias in Patients with Focal Ectopy Originating from the Pulmonary Veins

JOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2001
MARC ZIMMERMANN M.D.
Autonomic Variations in Focal AF. Introduction: This study was designed to analyze dynamic changes in autonomic tone preceding the onset of sustained atrial arrhythmias in patients with focal atrial fibrillation (AF) to determine why patients with frequent discharge from the arrhythmogenic foci develop sustained AF. Methods and Results: Holter tapes from 13 patients (10 men and 3 women; mean age 53 ± 5 years) with paroxysmal "lone" AF (mean 18 ± 13 episodes per week) and a proven focal origin (pulmonary veins in all cases) were analyzed. A total of 38 episodes of sustained AF (> 30 min) were recorded and submitted to frequency-domain heart rate variability analysis. Six periods were studied using repeated measures analysis of variance: the 24,hour period, the hour preceding AF, and the 20 minutes before AF divided into four 5,minute periods. A significant increase in high-frequency (HF, HF-NU) components was observed during the 20 minutes preceding AF (P = 0.003 and 0.002, respectively), together with a progressive decrease in normalized low-frequency (LF-NU) components (P = 0.035). An increase in LF/HF ratio followed by a linear decrease starting 15 minutes before sustained AF also was observed, indicating fluctuations in autonomic tone, with a primary increase in adrenergic drive followed by a marked modulation toward vagal predominance immediately before AF onset. Conclusion: In patients with focal ectopy originating from the pulmonary veins, sustained episodes of atrial arrhythmias are mainly dependent on variations of autonomic tone, with a significant shift toward vagal predominance before AF onset. [source]

Arterial Rigidity And Cardiovascular Sympathetic Tone In Hypertensive Obese And Type 2 Diabetic Patients

JOURNAL OF THE PERIPHERAL NERVOUS SYSTEM, Issue 3 2000
P Valensi
An increase of arterial rigidity and sympathetic activity has been suggested to contribute to essential hypertension. We have shown that vagal control of heart rate (HR) variations during standardized tests is similarly impaired in normotensive obese and type 2 diabetic patients. The aim was to compare cardiovascular vagosympathetic balance and the link between pulse pressure, an index of arterial rigidity, and sympathetic activity in normotensive and hypertensive obese and type 2 diabetic patients. Groups 1 and 2 consisted of 70 normotensive and 32 hypertensive obese patients, groups 3 and 4 of 18 normotensive and 14 hypertensive diabetic patients respectively. HR and blood pressure (BP) variations were studied with a plethysmographic system and spectral analysis (Finapres). During a 5 min-period at a controlled breathing rate, in the 4 groups, the high frequency peak of HR variations (vagal control) was significantly lower than in controls (19 healthy subjects), and the mid/high frequency peak ratio of HR variations was significantly increased. During a standing test, the mid-frequency peak of systolic BP variations (sympathetic activity) did not differ significantly in obese or diabetic patients, either normotensive or hypertensive, and in controls. This peak correlated significantly with pulse pressure in groups 2 and 4 and in the control group but not in groups 1 and 3. In conclusion, 1) spectral analysis confirms that in obese and diabetic patients vagal control of HR variations is similarly reduced and suggests that sympathetic activity is relatively increased ; 2) in hypertensive patients sympathetic tone is not higher than in normotensive ones, but may contribute to arterial rigidity. [source]

The Role of K+ Channels in Determining Pulmonary Vascular Tone, Oxygen Sensing, Cell Proliferation, and Apoptosis: Implications in Hypoxic Pulmonary Vasoconstriction and Pulmonary Arterial Hypertension

MICROCIRCULATION, Issue 8 2006
ROHIT MOUDGIL
ABSTRACT Potassium channels are tetrameric, membrane-spanning proteins that selectively conduct K+ at near diffusion-limited rates. Their remarkable ionic selectivity results from a highly-conserved K+ recognition sequence in the pore. The classical function of K+ channels is regulation of membrane potential (EM) and thence vascular tone. In pulmonary artery smooth muscle cells (PASMC), tonic K+ egress, driven by a 145/5 mM intracellular/extracellular concentration gradient, contributes to a EM of about ,60 mV. It has been recently discovered that K+ channels also participate in vascular remodeling by regulating cell proliferation and apoptosis. PASMC express voltage-gated (Kv), inward rectifier (Kir), calcium-sensitive (KCa), and two-pore (K2P) channels. Certain K+ channels are subject to rapid redox regulation by reactive oxygen species (ROS) derived from the PASMC's oxygen-sensor (mitochondria and/or NADPH oxidase). Acute hypoxic inhibition of ROS production inhibits Kv1.5, which depolarizes EM, opens voltage-sensitive, L-type calcium channels, elevates cytosolic calcium, and initiates hypoxic pulmonary vasoconstriction (HPV). Hypoxia-inhibited K+ currents are not seen in systemic arterial SMCs. Kv expression is also transcriptionally regulated by HIF-1, and NFAT. Loss of PASMC Kv1.5 and Kv2.1 contributes to the pathogenesis of pulmonary arterial hypertension (PAH) by causing a sustained depolarization, which increases intracellular calcium and K+, thereby stimulating cell proliferation and inhibiting apoptosis, respectively. Restoring Kv expression (via Kv1.5 gene therapy, dichloroacetate, or anti-survivin therapy) reduces experimental PAH. Electrophysiological diversity exists within the pulmonary circulation. Resistance PASMC have a homogeneous Kv current (including an oxygen-sensitive component), whereas conduit PASMC current is a Kv/KCa mosaic. This reflects regional differences in expression of channel isoforms, heterotetramers, splice variants, and regulatory subunits as well as mitochondrial diversity. In conclusion, K+ channels regulate pulmonary vascular tone and remodeling and constitute potential therapeutic targets in the regression of PAH. [source]

Regulation of In Situ Skeletal Muscle Arteriolar Tone: Interactions Between Two Parameters

MICROCIRCULATION, Issue 6 2002
JEFFERSON C. FRISBEEArticle first published online: 26 JAN 2010
ABSTRACT Objective: The growing understanding of the complexity of mechanisms regulating arteriolar tone demands that a systematic determination of how these processes interact to alter diameter be undertaken. This study examined how five mediators of skeletal muscle distal arteriolar tone [adenosine concentration, oxygen content, ,-adrenergic activation (norepinephrine), intravascular pressure and wall shear rate], taken two parameters at a time, interact to regulate vessel diameter. Methods: The reactivity of distal arterioles of in situ rat cremaster muscle after alterations in each of the above mediators was assessed. In addition, arteriolar responses to all two-parameter combinations were evaluated to determine the effect of altered environment on vascular reactivity to stimuli. Results: Arteriolar dilation to adenosine was unaltered by changes in other parameters. In contrast, wall shear rate-induced arteriolar dilation was impaired by 60,88% after increases in the other parameters. Myogenic reactivity was reduced by 28% with elevated O2 and by 65% with norepinephrine (because of vessel closure) and was impaired by 89% with elevated adenosine. O2 -induced arteriolar reactivity was impaired by 56% with increased adenosine and by 44% with increased norepinephrine concentration but was largely unaffected by elevated intravascular pressure. Adrenergic reactivity was attenuated with elevated intravascular pressure (by 69%) and O2 (by 54%) because of vessel closure but was unaltered with elevated adenosine. Conclusions: These data suggest that (1) individual mediators contributing to the regulation of arteriolar tone exist within a hierarchy of importance and (2) mechanisms regulating arteriolar tone can be impacted by unidentified alterations in other processes. Ongoing investigation into interactions between multiple processes regulating arteriolar tone will allow for a more integrated understanding of how microvessels regulate their diameter. [source]

Exposure to Interparental Conflict and Children's Adjustment and Physical Health: The Moderating Role of Vagal Tone

CHILD DEVELOPMENT, Issue 6 2001
Mona El-Sheikh
Physiological regulation, as indexed by baseline vagal tone and delta vagal tone (the change in vagal tone during an attention-demanding or challenging task), was examined as a moderator in the relations between exposure to verbal and physical parental marital conflict and children's adjustment and physical health. Higher vagal tone was posited to serve a protective function (i.e., buffer) for children exposed to higher levels of marital conflict. Seventy-five 8- to 12-year-olds and their mothers completed measures of parental conflict, and children's adjustment and physical health. Children's vagal tone was assessed during baseline conditions and during exposure to an audiotaped interadult argument. Results indicate that higher vagal tone buffered children against increased externalizing, internalizing, and health problems related to exposure to more frequent marital conflict, especially verbal conflict. Further, higher levels of delta vagal tone protected boys against externalizing problems associated with verbal conflict, and health problems associated with physical conflict. [source]

Effect Of Anti-Oxidant Treatment And Cholesterol Lowering On Resting Arterial Tone, Metabolic Vasodilation And Endothelial Function In The Human Forearm: A Randomized, Placebo-Controlled Study

CLINICAL AND EXPERIMENTAL PHARMACOLOGY AND PHYSIOLOGY, Issue 5-6 2001
Stephen J Duffy
SUMMARY 1. The aim of the present study was to determine whether anti-oxidant therapy with vitamin E and/or cholesterol-lowering therapy with simvastatin would augment resting forearm blood flow (FBF) and metabolic vasodilation in response to exercise and improve endothelial function in young patients with hypercholesterolaemia. 2. Endothelium-dependent and -independent, nitric oxide (NO)-mediated vasodilation have been shown to be impaired in young, otherwise healthy subjects with hypercholesterolaemia. Recent experimental and clinical studies suggest that vascular function may be improved with anti-oxidant or cholesterol- lowering therapy, although these treatments may be synergistic. 3. We compared FBF at rest, in response to isotonic exercise, the endothelium-dependent vasodilator acetylcholine (ACh), the endothelium-independent vasodilator sodium nitroprusside (SNP) and the NO synthase inhibitor NG -monomethyl- L -arginine (L -NMMA) in 26 young, otherwise healthy volunteers (mean (±SD) age 29±7 years; 14 female, 12 male) with hypercholesterolaemia, before and after 6 months treatment with vitamin E, simvastatin and/or placebo. Treatment was randomized, double-blinded in a 2 × 2 factorial design. Forearm blood flow was measured using venous occlusion plethysmography. 4. Vitamin E therapy increased plasma ,-tocopherol from 39.5±9.6 to 75.7±33.8 ,mol/L (P < 0.001). Simvastatin reduced total cholesterol from 6.9±1.7 to 4.9±0.8 mmol/L and low- density lipoprotein (LDL) from 4.8±1.7 to 3.0±0.7 mmol/L (both P < 0.001), although total and LDL,cholesterol also decreased slightly in the placebo group. Vitamin E increased resting FBF from 2.1±0.3 to 2.4±0.3 mL/100 mL per min (P = 0.04) and decreased resting forearm vascular resistance from 42.1±4.2 to 36.1±3.4 units (P = 0.01), but the reduction in resting FBF with L -NMMA was not affected. Vasodilation in response to isotonic exercise, ACh and SNP was similar before and after treatment in the placebo, vitamin E, simvastatin and in the combined vitamin E,simvastatin groups. NG -Monomethyl- L -arginine infusion reduced resting FBF and functional hyperaemia in response to exercise and these responses were not altered by treatment. 5. These data suggest that while vitamin E therapy augments resting FBF and reduces forearm vascular resistance in young hypercholesterolaemic subjects, these effects may not be via NO-dependent pathways. Metabolic vasodilation and responses to the NO-mediated vasodilators ACh and SNP were not favourably affected by anti-oxidant or cholesterol-lowering therapy, either alone or in combination. [source]

Towards High Order Numerical Simulation of Aeolian Tones

PROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005
Bernhard Müller
Strictly stable high order finite difference operators have been applied to the compressible Navier-Stokes equations in perturbation form for low Mach number computational aeroacoustics. Aeolian tones generated by vortex shedding from a circular cylinder have been simulated. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Prepulse inhibition of startle, intelligence and familial primary nocturnal enuresis

ACTA PAEDIATRICA, Issue 4 2000
EM Ornitz
Previous studies have shown a significant reduction of prepulse inhibition of startle in boys with primary nocturnal enuresis. Those enuretic boys who had higher IQs showed less prepulse inhibition. This study evaluates the association of prepulse inhibition and IQ in primary nocturnal enuresis in respect to family history of primary nocturnal enuresis. Prepulse inhibition of startle was studied in 83 boys with primary nocturnal enuresis and 57 non-enuretic boys using an interval of 120 ms between the onset of a 75 dB 1000 Hz tone and a 104 dB noise burst. Of the boys with primary nocturnal enuresis, 56 had a family history of primary nocturnal enuresis and 27 had no family history (no first-degree relative). Of the 57 non-enuretic boys, 42 also had no family history (no first-degree relative) of primary nocturnal enuresis, while 15 did have a positive family history. Associations between prepulse inhibition and IQ scores were compared among these four groups. Strong and significant associations between prepulse inhibition deficit and higher IQ scores in the enuretic group with familial primary nocturnal enuresis were unique in comparison to the other groups. Conclusions: The strong heritabilities of primary nocturnal enuresis, intelligence and prepulse inhibition suggest genetic mediation of the association of prepulse inhibition with intelligence in familial primary nocturnal enuresis. [source]

Adenosine A1 receptors and vascular reactivity

ACTA PHYSIOLOGICA, Issue 2 2010
Y. Wang
Abstract Aim:, Blood pressure is higher in A1 receptor knock-out (A1R,/,) mice than in wild type litter mates (A1R+/+) and we have examined if this could be related to altered vascular functions. Methods:, Contraction of aortic rings and mesenteric arteries were examined. To examine if the adenosine A1 receptor-mediated contraction of aortic muscle was functionally important we examined pulse pressure (PP) and augmentation index (AIX) using a sensor that allows measurements of rapid pressure transients. Results:, Contraction of aortic rings to phenylephrine and relaxation to acetylcholine were similar between genotypes. The non-selective adenosine receptor agonist N -ethyl carboxamido adenosine (NECA) enhanced the contractile response, and this was eliminated in aortas from A1R,/, mice. However, in mesenteric arteries no contractile response was seen and adenosine-mediated relaxation was identical between studied genotypes. A2B adenosine receptors, rather than A2A receptors, may be mainly responsible for the vasorelaxation induced by adenosine analogues in the examined mouse vessels. PP was higher in A1R,/, mice, but variability was unaltered. AIX was not different between genotypes, but the NECA-induced fall was larger in A1R,/, mice. Conclusions:, The role of adenosine A1 receptors in regulating vessel tone differs between blood vessels. Furthermore, contractile effects on isolated vessels cannot explain the blood pressure in A1 knock-out mice. The A1 receptor modulation of blood pressure is therefore mainly related to extravascular factors. [source]

Endothelin attenuates endothelium-dependent platelet inhibition in man

ACTA PHYSIOLOGICA, Issue 4 2010
R. E. Malmström
Abstract Aim:, The vascular endothelium produces several substances, including nitric oxide (NO) and endothelin-1 (ET-1), which participate in the regulation of vascular tone in humans. Both these substances may exert other actions of importance for cardiovascular disease, e.g. effects on vascular smooth muscle cell proliferation and inflammation, and NO inhibits platelet function. Experiments were designed to investigate the effect of ET-1 on endothelium-dependent vasodilatation and attenuation of platelet activation. Methods:, In 25 healthy male subjects (25 ± 1 years), forearm blood flow was measured by venous occlusion plethysmography, and platelet activity was assessed by whole blood flow cytometry (platelet fibrinogen binding and P-selectin expression) in unstimulated and adenosine diphosphate (ADP)-stimulated samples during administration of ET-1, the endothelium-dependent vasodilator acetylcholine and the NO synthase inhibitor l -NMMA. Results:, Acetylcholine increased forearm blood flow and significantly inhibited platelet activation in both unstimulated and ADP-stimulated samples. In samples stimulated with 0.3 ,m ADP, fibrinogen binding decreased from 41 ± 4% to 31 ± 3% (P < 0.01, n = 11) after acetylcholine administration. The vasodilator response to acetylcholine was significantly impaired during infusions of ET-1 and l -NMMA. ET-1 did not affect platelet activity per se, whereas l -NMMA increased platelet P-selectin expression. Both ET-1 and l -NMMA attenuated the acetylcholine-induced inhibition of platelet activity. Conclusions:, Our study indicates that, further to inhibiting endothelium-dependent vasodilatation, ET-1 may also attenuate endothelium-dependent inhibition of platelet activation induced by acetylcholine. An enhanced ET-1 activity, as suggested in endothelial dysfunction, may affect endothelium-dependent platelet modulation and thereby have pathophysiological implications. [source]

Cardiac autonomic function and baroreflex changes following 4 weeks of resistance versus aerobic training in individuals with pre-hypertension

ACTA PHYSIOLOGICA, Issue 3 2009
S. R. Collier
Abstract Aim:, Cardiac autonomic modulation and baroreflex sensitivity (BRS) are altered in individuals with hypertension. Aerobic exercise (AE) training has been shown to improve both measures, yet little is known about the effects of resistance exercise (RE). The purpose of this study was to examine the heart rate variability (HRV) and BRS following 4 weeks of resistance or aerobic training in a population with borderline high blood pressure (BP). Methods:, Twenty-nine mild hypertensives were recruited and randomly assigned to 4 weeks of RE or AE training. Before and after training, resting measures of HRV frequencies and BRS were obtained. Results:, There was a significant decrease in resting systolic BP for both exercise training modes (RE 136 ± 3.0 pre- to 132 ± 3.4 post-training vs. AE 142 ± 4.0 pre- to 137 ± 3.6 mmHg post-training, P = 0.019). Diastolic BP decreased significantly following both exercise training modes (RE 78 ± 1.31 pre to 74 ± 1.1 post vs. AE 80 ± 1.7 pre to 77 ± 1.6 mmHg post, P = 0.002). A significant time by training mode interaction for low frequency : high frequency (HF) ratio (P = 0.017) with AE decreasing the ratio (275.21 ± 67.28 to 161.26 ± 61.49) and RE increasing this ratio (143.73 ± 65.00 to 227.83 ± 59.41). Natural log-transformed (ln) HRV values showed a time-by-training mode interaction for ln HF (P = 0.05) as ln HF increased (4.7 ± 0.38 to 5.4 ± 0.35 ms2) following AE and decreased (5.98 ± 0.37 to 5.76 ± 0.42 ms2) following RE. BRS increased following aerobic training and decreased after resistance training (6.74 ± 1.2 to 7.94 ± 1.3 and 10.44 ± 1.2 to 9.1 ± 1.2 ms mmHg,1 respectively, P = 0.021). Conclusions:, Aerobic exercise improved the autonomic nervous system (increasing vagal tone, reducing sympathovagal balance while increasing BRS) while RE showed no improvements in cardiac autonomic tone and decreased BRS. [source]

Calcium handling in afferent arterioles

ACTA PHYSIOLOGICA, Issue 4 2004
M. Salomonsson
Abstract The cytosolic intracellular calcium concentration ([Ca2+]i) is a major determining factor in the vascular smooth muscle tone. In the afferent arteriole it has been shown that agonists utilizing G-protein coupled receptors recruit Ca2+ via release from intracellular stores and entry via pathways in the plasma membrane. The relative importances of entry vs. mobilization seem to differ between different agonists, species and preparations. The entry pathway might include different types of voltage sensitive Ca2+ channels located in the plasmalemma such as dihydropyridine sensitive L-type channels, T-type channels and P/Q channels. A role for non-voltage sensitive entry pathways has also been suggested. The importance of voltage sensitive Ca2+ channels in the control of the tone of the afferent arteriole (and thus in the control of renal function and whole body control of extracellular fluid volume and blood pressure) sheds light on the control of the membrane potential of afferent arteriolar smooth muscle cells. Thus, K+ and Cl, channels are of importance in their role as major determinants of membrane potential. Some studies suggest a role for calcium-activated chloride (ClCa) channels in the renal vasoconstriction elicited by agonists. Other investigators have found evidence for several types of K+ channels in the regulation of the afferent arteriolar tone. The available literature in this field regarding afferent arterioles is, however, relatively sparse and not conclusive. This review is an attempt to summarize the results obtained by others and ourselves in the field of agonist induced afferent arteriolar Ca2+ recruitment, with special emphasis on the control of voltage sensitive Ca2+ entry. Outline of the Manuscript: This manuscript is structured as follows: it begins with an introduction where the general role for [Ca2+]i as a key factor in the regulation of the tone of vascular smooth muscles (VSMC) is detailed. In this section there is an emphasis is on observations that could be attributed to afferent arteriolar function. We then investigate the literature and describe our results regarding the relative roles for Ca2+ entry and intracellular release in afferent arterioles in response to vasoactive agents, with the focus on noradrenalin (NA) and angiotensin II (Ang II). Finally, we examine the role of ion channels (i.e. K+ and Cl, channels) for the membrane potential, and thus activation of voltage sensitive Ca2+ channels. [source]

Contribution of Na+/Ca2+ exchanger to the regulation of myogenic tone in isolated rat small arteries

ACTA PHYSIOLOGICA, Issue 2 2001
S. Horiguchi
The contribution of the Na+/Ca2+ exchanger to the myogenic vascular tone was examined in rat isolated skeletal muscle small arteries (ASK) with pronounced myogenic tone and mesenteric small arteries (AMS) with little myogenic tone. Myogenic tone was assessed by the vascular inner diameter at transmural pressures of 40 and 100 mmHg. To depress the Na+/Ca2+ exchanger, the extracellular Na+ concentration ([Na+]o) was lowered from 143 to 1.2 mM by substituting choline-Cl for NaCl. The ASK developed significant myogenic tone and constricted further in low [Na+]o. Nifedipine (1 ,M) reduced both myogenic tone and low [Na+]o-induced contraction. Because the membrane potential of ASK was not changed by low [Na+]o (,35 ± 2 mV at 143 mM [Na+]o, ,37 ± 3 mV at 1.2 mM [Na+]o), depolarization-induced Ca2+ influx was not a cause of the low [Na+]o-induced contraction. The AMS did not develop significant myogenic tone. Although low [Na+]o also constricted AMS, the magnitude of constriction was significantly weaker than that in ASK (17 ± 4 vs. 47 ± 6%, P < 0.01, at 58 mM Na+). With Bay K 8644, AMS developed myogenic tone, and low [Na+]o-induced constriction was significantly increased. In conclusion, Na+/Ca2+ exchanger may play an important role in regulating myogenic tone, likely via mediating Ca2+ -extrusion. [source]

Botulinum Toxin for the Treatment of Facial Flushing

DERMATOLOGIC SURGERY, Issue 1 2004
Melanie Yuraitis MS
Background. Facial flushing is a common problem that is encountered by fair-skinned patients of Celtic and Northern European descent. Although usually transient in nature, some patients display a persistent reddened skin tone, with periods of increased erythema. Treatment of this condition is limited. Objective. To describe a novel method for the treatment of persistent facial flushing. Method. We report a case of persistent facial flushing that was resistant to multiple pulsed dye laser treatments and was successfully treated with botulinum toxin A. Results. The posttreatment appearance was dramatic, and the patient was highly satisfied with the cosmetic outcome. Conclusion. Botulinum toxin A can be used in small quantities to decrease persistent facial flushing temporarily. [source]

Multipass Treatment of Photodamage Using the Pulse Dye Laser

DERMATOLOGIC SURGERY, Issue 7 2003
Emil A. Tanghetti MD
Background. Pulse dye lasers (PDLs) alter structural proteins in scars and photodamaged skin, in addition to their effects on dermal vasculature. The PDL has become an option in the treatment of photodamage. Although improvements to skin texture are generally modest when compared with ablative resurfacing, PDL offers a treatment with few side effects. A number of methods have been proposed in an effort to improve treatment outcomes. These range from single, low-fluence treatment with no purpura to multiple passes and treatment sessions as well as purpuric doses. Objective. To evaluate several of the PDL treatment methods to improve photorejuvenation outcomes while limiting the risk of side effects. Methods. Twenty patients with photodamage were separated into two groups. Each group received a series of four single-pass treatments or four double-pass treatments at 2-week intervals. Treatments were done using a 595-nm PDL (PhotoGenica V-Star) and a 585-nm PDL (PhotoGenica V) at a pulse duration of 0.5 ms and a 10-mm handpiece. Treatment fluences were maintained below the individual's purpuric threshold, ranging from 3 to 4 J/cm2. Photos were taken before treatment and during follow-up. Efficacy of treatment was based on subjective grading of photos and by patient self-reporting. Results. Multiple treatments resulted in improvements to skin tone and texture, including a reduction in the appearance of rhytids and, in particular, improved pigmentary evenness. There was no significant difference between laser or treatment methods. No side effects were noted. Conclusion. PDL treatments provide effective photorejuvenation with minimal risk of side effects. [source]

Decreased Tear Expression with an Abnormal Schirmer's Test Following Botulinum Toxin Type A for the Treatment of Lateral Canthal Rhytides

DERMATOLOGIC SURGERY, Issue 2 2002
Seth L. Matarasso MD
background. Inactivation of muscles of facial expression by chemodenervation with botulinum toxin remains an off-label indication. Nevertheless, it continues to be a safe and effective technique to improve dynamic rhytides and is the treatment of choice for the hypertrophic lateral fibers of the orbicularis oculi muscle that can cause the superimposed crow's feet. objective. Although infrequent and self-limiting, the complication of unexpected muscle weakness from toxin diffusion or erroneous placement is documented. methods. However, injection into the pretarsal portion of the orbicularis oculi muscle resulting in unilateral ocular irritation and diminished tear expression as evidenced by a dry eye and an abnormal Schirmer's test has rarely been reported. Direct injection into the pretarsal fibers of the muscle as opposed to diffusion of the toxin into the muscle fibers or the lacrimal gland was consistent with the onset of action of the toxin and the prolonged duration of the ocular symptoms. results. Treatment consisted of ocular lubrication until the effects of the toxin dissipated and muscle tone returned. Subsequent treatment did not result in a result in a recurrence of adverse sequelae. conclusions. Facial muscles are small, not isolated, and often have fibers that interdigitate. An important factor in the administration of botulinum toxin is the identification of the muscles responsible for the corresponding rhytide. Precise knowledge of muscular anatomy and function will aid in minimizing this and other potential complications. [source]

Oral Isotretinoin as Part of the Treatment of Cutaneous Aging

DERMATOLOGIC SURGERY, Issue 7 2000
Enrique Hernandez-Perez MD
Background. A number of drugs have been used to prevent aging changes. However, studies of oral isotretinoin, the commonly used acne drug, as an antiaging drug are lacking. Objective. To determine improvement in cutaneous aging utilizing oral isotretinoin combined with different procedures of facial rejuvenation. Methods. Sixty patients ranging in age from 35 to 65 years, in whom additional modalities of rejuvenation were also used, were randomly assigned to receive treatment with oral isotretinoin (10,20 mg three times a week for 2 months, group A). Their results were compared with 60 patients who had undergone the same surgical procedures but with no oral isotretinoin (group B). Results. All patients treated with oral isotretinoin noted improvement in wrinkles, thickness and color of the skin, size of pores, skin elasticity, tone, and reduction in pigmented lesions and mottled hyperpigmentation. A statistically significant difference was found in the improvement of group A (Wilcoxon test <0.01). Using minimal amounts of this drug, the side effects were practically negligible. Conclusion. Utilizing various procedures with oral isotretinoin allowed us to improve the effects of cutaneous aging. Our results using isotretinoin in these cases have been satisfactory. We believe that this is one of the first reports of the use of oral isotretinoin in intrinsic and photoaged skin. [source]

Intrathecal baclofen use in adults with cerebral palsy

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2009
LINDA E KRACH MD
Intrathecal baclofen (ITB) is an effective treatment for both spasticity and dystonia in people with cerebral palsy (CP). Its use is becoming increasingly common. ITB is typically associated with fewer side effects than the oral form of the product, but there are risks related to the hardware needed for intrathecal delivery. Much of what has been reported in the literature about ITB is based on experience with children or groups of children and adults; few reports exclusively address its use in adults with CP. These reports indicate that muscle tone is consistently reduced, but there is some variability in functional outcomes. Few well-controlled studies have been done. Controversies remain concerning ITB, including whether a trial is needed before pump implantation, proper catheter tip placement, and programming options, as well as whether it contributes to the development or progression of scoliosis. These and other unanswered questions should be addressed in a systematic way. [source]

Long-term effects of botulinum toxin A in children with cerebral palsy

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 2 2009
KRISTINA TEDROFF MD
The long-term effects of botulinum toxin A (BoNT-A) treatment in children with cerebral palsy (CP) are still elusive. We studied a prospective clinical cohort of 94 children with different subtypes (50% spastic diplegic CP, 22% hemiplegic CP, 25% tetraplegic CP, 3% dyskinetic CP), sex (55% male, 45% female), severity according to Gross Motor Function Classification System (29% Level I, 15% Level II, 16% Level III, 17% Level IV, 23% Level V), and age (median 5y 4mo, range 11mo,17y 8mo). The longest follow-up time was 3 years 7 months (median 1y 6mo) and included a maximum of eight injections per muscle (median two injections to a specific muscle). Outcome measurements were muscle tone (Modified Ashworth Scale) and joint range of motion (ROM). Assessments were made at a minimum before and 3 months after each injection. Ninety-five per cent confidence intervals for differences from baseline were used to identify significant changes. BoNT-A injections induced reduction of long-term spasticity in all muscle-groups examined: the gastrocnemius, hamstring, and adductor muscles. The reduction in tone was most distinct in the gastrocnemius muscle, and each repeated injection produced an immediate reduction in muscle tone. However, improvement in ROM was brief and measured only after the first injections, whereupon the ROM declined. Thus, the results suggest that BoNT-A can be effective in reducing muscle tone over a longer period, but not in preventing development of contractures in spastic muscles. The dissociation between the effects on muscle tone and ROM indicates that development of contractures is not coupled to increased muscle tone only, but might be caused by other mechanisms. [source]

Abnormalities in cardiac and respiratory function observed during seizures in childhood

DEVELOPMENTAL MEDICINE & CHILD NEUROLOGY, Issue 1 2005
Mary E O'Regan MRCP MRCPCH
The aim of this study was to observe any changes in cardiac and respiratory function that occur during seizures. Thirty-seven children (20 males, 17 females; median age 7y 6mo, range 1y 6mo to 15y 6mo) were studied. We recorded electroencephalograms, respiratory rate, heart rate, electrocardiograms, blood pressure, oxygen saturation, heart rate variability (time domain analysis), and cardiac vagal tone. A respiratory pause was defined as an interruption in respiration lasting more than 3s but less than 15s. Apnoea was defined as absence of respiration for more than 15s. Tachypnoea was defined as a 10% increase in respiratory rate from the pre-ictal baseline. Bradypnoea was defined as a 10% decrease in respiratory rate from the pre-ictal baseline. Significant hypoxia was defined as a saturation of less than 85%. A significant change in heart rate was taken as a 10% increase or decrease below the baseline rate. Data were obtained from 101 seizures: 40 focal seizures, 21 generalized seizures, and 40 absences. Focal seizures were frequently associated with significant respiratory abnormalities, tachypnoea in 56%, apnoea in 30%, frequent respiratory pauses in 70%, and significant hypoxaemia in 40%. The changes seen in respiratory rate were statistically significant. Changes in cardiac parameters, an increase or decrease in heart rate, were observed in only 26% of focal seizures and 48% of generalized seizures. We conclude that seizure activity can disrupt normal physiological regulation and control of respiratory and cardiac activity. [source]

Stability of resting frontal electroencephalogram (EEG) asymmetry and cardiac vagal tone in adolescent females exposed to child maltreatment

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 6 2009
Vladimir Miskovic
Abstract The experience of child maltreatment is a known risk factor for the development of psychopathology. Structural and functional modifications of neural systems implicated in stress and emotion regulation may provide one mechanism linking early adversity with later outcome. The authors examined two well-documented biological markers of stress vulnerability [resting frontal electroencephalogram (EEG) asymmetry and cardiac vagal tone] in a group of adolescent females exposed to child maltreatment (n,=,38; M age,=,14.47) and their age-matched non-maltreated (n,=,25; M age,=,14.00) peers. Maltreated females exhibited greater relative right frontal EEG activity and lower cardiac vagal tone than controls over a 6-month period. In addition, frontal EEG asymmetry and cardiac vagal tone remained stable in the maltreated group across the 6 months, suggesting that the neurobiological correlates of maltreatment may not simply reflect dynamic, short-term changes but more long lasting alterations. The present findings appear to be the first to demonstrate stability of two biologically based stress-vulnerability measures in a maltreated population. Findings are discussed in terms of plasticity within the neural circuits of emotion regulation during the early childhood period and alternative causal models of developmental psychopathology. © 2009 Wiley Periodicals, Inc. Dev Psychobiol 51: 474,487, 2009 [source]

Cross-Modal transfer of the conditioned eyeblink response during interstimulus interval discrimination training in young rats

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 7 2008
Kevin L. Brown
Abstract Eyeblink classical conditioning (EBC) was observed across a broad developmental period with tasks utilizing two interstimulus intervals (ISIs). In ISI discrimination, two distinct conditioned stimuli (CSs; light and tone) are reinforced with a periocular shock unconditioned stimulus (US) at two different CS,US intervals. Temporal uncertainty is identical in design with the exception that the same CS is presented at both intervals. Developmental changes in conditioning have been reported in each task beyond ages when single-ISI learning is well developed. The present study sought to replicate and extend these previous findings by testing each task at four separate ages. Consistent with previous findings, younger rats (postnatal day,PD23 and 30) trained in ISI discrimination showed evidence of enhanced cross-modal influence of the short CS,US pairing upon long CS conditioning relative to older subjects. ISI discrimination training at PD43,47 yielded outcomes similar to those in adults (PD65,71). Cross-modal transfer effects in this task therefore appear to diminish between PD30 and PD43,47. Comparisons of ISI discrimination with temporal uncertainty indicated that cross-modal transfer in ISI discrimination at the youngest ages did not represent complete generalization across CSs. ISI discrimination undergoes a more protracted developmental emergence than single-cue EBC and may be a more sensitive indicator of developmental disorders involving cerebellar dysfunction. © 2008 Wiley Periodicals, Inc. Dev Psychobiol 50: 647-664, 2008. [source]

Physiological and neuropsychological correlates of approach/withdrawal tendencies in preschool: Further examination of the behavioral inhibition system/behavioral activation system scales for young children

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 3 2004
Clancy Blair
Abstract This study examined a parent-report version of the Behavioral Inhibition System/Behavioral Activation System (BIS/BAS) scales, a measure of approach,withdrawal motivation, in 170 children between the ages of 3 to 5 years attending Head Start programs. Physiological measures included assessments of baseline salivary cortisol and change in cortisol in response to the assessment session, and resting and suppression estimates of cardiac vagal tone. Cognitive self-regulation was assessed with a peg-tapping measure of inhibitory control and an item-selection measure of cognitive set-shifting ability. Results indicated that higher level of parent-reported withdrawal motivation was associated with cortisol increase and that parent-reported approach motivation tended to be associated with cortisol decrease across the assessment session. Higher level of parent-reported withdrawal also was positively related to cognitive self-regulation while parent-reported approach was negatively related to cognitive self-regulation. Person-oriented analysis indicated that children characterized by both high level of approach and high level of withdrawal tended to exhibit lower resting vagal tone, higher initial cortisol, and minimal cortisol and vagal change. Overall, findings suggest that the parent-report version of the BIS/BAS scales works well as an indicator of children's reactivity to appetitive and aversive motivational stimuli. Directions for future research and implications of findings for the longitudinal study of temperament and personality are discussed. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 45: 113-124, 2004. [source]

Children's narratives and patterns of cardiac reactivity

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 4 2004
Yair Bar-Haim
Abstract The present study examines the associations between narrative processing, narrative production, and cardiac rate and variability in children. Heart period (HP) and vagal tone (VT) were computed for fifty-eight 7-year-olds (29 males) during a resting baseline and during epochs in which the children listened to and completed a selected set of story-stems from the MacArthur Story-Stem Battery (I. Bretherton, D. Oppenheim, H. Buchsbaum, R. N. Emde, & the MacArthur Narrative Group, 1990). Significant decreases in HP and VT were observed between a resting baseline and epochs of story-stem presentation by the experimenter. In addition, HP was shorter and VT lower during children's narrative production to emotionally laden story-stems compared with narration to a neutral story-stem. Furthermore, narrative and cardiac responses to stories containing separation,reunion themes reflected increased emotional and cognitive load compared with responses to stories that did not contain such themes. Finally, children who showed VT suppression in response to emotion-laden stories produced more coherent and adaptive narratives compared to those of children who did not show VT suppression. The findings suggest interplay between the cognitive-emotional processes associated with narrative processing and production and cardiac activation patterns. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 238,249, 2004. [source]

Associative learning and memory in a chimpanzee fetus: Learning and long-lasting memory before birth

DEVELOPMENTAL PSYCHOBIOLOGY, Issue 2 2004
Nobuyuki Kawai
Abstract We tested whether a chimpanzee fetus could form an association between an extrauterine tone and vibroacoustic stimulation (VAS) using classical conditioning treatment. Two kinds of pure tone were used as the conditioned stimuli, one where a 500-Hz tone was always followed by a VAS of 80 Hz (110 gal), the unconditioned stimulus (US), and another where a 1000-Hz tone was never followed by a VAS. This treatment was repeated 156 times in total until natural labor at 233 days of gestational age. Behavioral tests on the 33rd and 58th days after birth revealed a differential response to the tones: The infant displayed an exaggerated response to the 500-Hz tone, but not to the 1000-Hz tone. Other naïve chimpanzee infants did not show any response to either tone, which suggests that a chimpanzee fetus can distinguish between tones and form an association, and that it retains such information for at least 2 months after birth. © 2004 Wiley Periodicals, Inc. Dev Psychobiol 44: 116,122, 2004. [source]