NO Synthesis (no + synthesis)

Distribution by Scientific Domains
Distribution within Medical Sciences

Selected Abstracts

Butanolides from Machilus thunbergii and their inhibitory activity on nitric oxide synthesis in activated macrophages

Nam Yi Kim
Abstract In activated macrophages the inducible form of nitric oxide synthase (iNOS) generates high amounts of the toxic mediator, nitric oxide (NO), that contributes to the circulatory failure associated with septic shock. Three butanolides were isolated from Machilus thunbergii as active principles which inhibit the production of NO in lipopolysaccharide-activated RAW 264.7 cells, and their structures were identi,ed as litsenolide A2 (1), B1 (2) and B2 (3). They showed dose-dependent inhibition of NO syntheses and the IC50s were 3.36, 3.70 and 6.19 µm, respectively. These new inhibitors of iNOS may have potential in the treatment of endotoxaemia and in,ammation accompanied by the overproduction of NO. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Role of shear stress on nitrite and NOS protein content in different size conduit arteries of swine

X. Guo
Abstract Aim:, Inherent fundamental difference exists among arteries of different sizes. The purpose of this study was to evaluate the relation between regional difference of wall shear stress (WSS) in various sizes arteries and contents of nitrite and NO synthase (NOS) isoforms. Methods:, Five different conduit arteries in a wide range of diameter (1,8 mm) were examined in the hind limbs of 13 pigs. Blood flow rate and outer diameter were measured in vivo to determine WSS. Arterial tissues were harvested for the measurement of nitrite and NOS protein contents. The concentration of nitrite, a product of NO synthesis, was determined by high-performance liquid chromatography method. Western blot analysis was used to assess the protein contents of endothelial NOS (eNOS), inducible NOS (iNOS) and neuronal NOS (nNOS). Results:, Our data show that WSS increases with a decrease in artery diameter. Nitrite level increases with increasing WSS and hence decreases with artery diameter. The eNOS protein contents decrease with an increase in diameter. No significant difference for iNOS and nNOS protein contents was found with different artery diameter. A significant positive correlation between tissue nitrite and eNOS protein contents was also observed. Finally, the WSS-normalized eNOS is not significantly different in various size vessels. Conclusion:, Regional difference in blood flow has no effect on iNOS and nNOS protein contents in these conduit arteries. Regional difference in eNOS expression and nitrite contents may be related to the WSS-induced NO by the endothelium under normal physiological conditions. [source]

Thaliporphine protects ischemic and ischemic-reperfused rat hearts via an NO-dependent mechanism

Li-Man Hung
Abstract In ischemia or ischemia-reperfusion (I/R), nitric oxide (NO) can potentially exert several beneficial effects. Thaliporphine, a natural alkaloid with Ca2+ channel-activating and Na+/K+ channel-blocking activities, increased NO levels and exerted cardioprotective action in ischemic or I/R rats. The role of NO in the cardioprotective actions of thaliporphine was assessed. The severity of rhythm disturbances and mortality in anesthetized rats with either coronary artery occlusion for 30 min, or 5 min followed by 30-min reperfusion, were monitored and compared in thaliporphine- vs. placebo-treated groups. Thaliporphine treatment significantly increased NO and decreased lactate dehydrogenase (LDH) levels in the blood during the end period of ischemia or I/R. These changes in NO and LDH levels by thaliporphine were associated with a reduction in the incidence and duration of ventricular tachycardia (VT) and ventricular fibrillation (VF) during ischemic or I/R period. The mortality of animals was also completely prevented by 1 × 10,8 moles/kg of thaliporphine. In animals subjected to 4 h of left coronary artery occlusion, 1 × 10,7 moles/kg of thaliporphine dramatic reduced cardiac infarct zone from 46 ± 6% to 7.1 ± 1.9%. Inhibition of NO synthesis with 3.7 × 10,6 moles/kg of N, -nitro-L-arginine methyl ester (L-NAME) abolished the beneficial effects of thaliporphine during 30 min or 4 h myocardial ischemia. However, the antiarrhythmic activity and mortality reduction efficacy of thaliporphine during reperfusion after 5 min of ischemia was only partially antagonized by L-NAME. These results showed that thaliporphine efficiently exerted the cardioprotections either in acute or prolonged coronary artery occlusion or occlusion-reperfusion situations. The fact that thaliporphine induced cardioprotective effects were abrogated by L-NAME indicates that NO is an important mediator for the cardioprotective effects of thaliporphine in acute or prolonged ischemia, whereas antioxidant activities may contribute to the protection of I/R injury. Drug Dev. Res. 52:446,453, 2001. © 2001 Wiley-Liss, Inc. [source]

Neuronal nitric oxide synthase (nNOS) mRNA is down-regulated, and constitutive NOS enzymatic activity decreased, in thoracic dorsal root ganglia and spinal cord of the rat by a substance P N-terminal metabolite

Katalin J. Kovacs
Abstract Nitric oxide (NO) in the spinal cord plays a role in sensory and autonomic activity. Pain induced by acetic acid in the abdominal stretch (writhing) assay and hyperalgesia associated with chronic pain are highly sensitive to NO synthase (NOS) inhibitors. Because substance P (SP) is released and up-regulated in some models of chronic pain, we hypothesized that an accumulation of SP metabolites may influence NOS expression and activity. To test this hypothesis, we examined the effect of intrathecally (i.t.) injected substance P (1-7) [SP(1-7)], the major metabolite of SP in the rat, on neuronal NOS (nNOS) mRNA in the thoracic and lumbar spinal cord, dorsal root ganglia (DRG) and on the corresponding constitutive NOS (cNOS) enzyme activity. Detected using quantitative RT-PCR, nNOS mRNA content in the thoracic spinal cord was decreased 6 h after injection of 5 µmol of SP(1-7) and returned to control 2 days later. In thoracic DRG, nNOS mRNA was reduced 48 h after SP(1-7). The cNOS enzymatic activity in thoracic spinal tissue was gradually decreased to a minimum at 72 h. Down-regulation of NOS by SP(1-7) in the thoracic area appears to be highly associated with capsaicin-sensitive primary afferent neurons. No similar changes in either parameter were measured in the lumbar area after SP(1-7). These data suggest that N-terminal SP fragments, which are known to cause long-term antinociception in the writhing assay, may do so by their ability to down-regulate NO synthesis along nociceptive pathways. [source]

Contribution of endothelium-derived hyperpolarizing factors to the regulation of vascular tone in humans

Jeremy Bellien
Abstract Endothelium plays a crucial role in the regulation of cardiovascular homeostasis through the release of vasoactive factors. Besides nitric oxide (NO) and prostacyclin, increasing evidences show that endothelium-derived hyperpolarizing factors (EDHF) participate in the control of vasomotor tone through the activation of calcium-activated potassium channels. In humans, the role of EDHF has been demonstrated in various vascular beds including coronary, peripheral, skin and venous vessels. The mechanisms of EDHF-type relaxations identified in humans involved the release by the endothelium of hydrogen peroxide, epoxyeicosatrienoic acids (EETs), potassium ions and electronical communication through the gap junctions. The role of EETs could be particularly important because, in addition contributing to the maintenance of the basal tone and endothelium-dependent dilation of conduit arteries, these factors share many vascular protective properties of NO. The alteration of which might be involved in the physiopathology of cardiovascular diseases. The evolution of EDHF availability in human pathology is currently under investigation with some results demonstrating an increase in EDHF release to compensate the loss of NO synthesis and to maintain the endothelial vasomotor function whereas others reported a parallel decrease in NO and EDHF-mediated relaxations. Thus, the modulation of EDHF activity emerges as a new pharmacological target and some existing therapies in particular those affecting the renin,angiotensin system have already been shown to improve endothelial function through hyperpolarizing mechanisms. In this context, the development of new specific pharmacological agents especially those increasing EETs availability may help to prevent endothelial dysfunction and therefore enhance cardiovascular protection in patients. [source]

Insulin resistance, a new target for nitric oxide-delivery drugs

Stéphane Cook
Abstract In the Western hemisphere, the incidence of insulin resistance and its complications has been growing rapidly and is reaching epidemic proportions. Over the past decade, evidence has accumulated, indicating that nitric oxide (NO) plays a key role in the regulation of metabolic and cardiovascular homeostasis. Defective endothelial nitric oxide synthase (eNOS) driven NO synthesis causes insulin resistance, arterial hypertension and dyslipidemia in mice, and characterizes insulin-resistant humans. On the other hand, stimulation of inducible nitric oxide synthase (iNOS) and NO overproduction in mice, may also cause metabolic insulin resistance, suggesting a Yin,Yang effect of NO in the regulation of glucose homeostasis. Here, we will review the evidence for this novel concept, and thereby provide the conceptual framework for the use of NO-delivery drugs and pharmacological agents that modulate the bioavailability of endogenously produced NO for the treatment of insulin resistance. [source]

Left ventricular hypertrophy in rats with biliary cirrhosis

HEPATOLOGY, Issue 3 2003
Javier Inserte
Portal hypertension induces neuroendocrine activation and a hyperkinetic circulation state. This study investigated the consequences of portal hypertension on heart structure and function. Intrahepatic portal hypertension was induced in male Sprague-Dawley rats by chronic bile duct ligation (CBDL). Six weeks later, CBDL rats showed higher plasma angiotensin-II and endothelin-1 (P < .01), 56% reduction in peripheral resistance and 73% reduction in pulmonary resistance (P < .01), 87% increase in cardiac index and 30% increase in heart weight (P < .01), and increased myocardial nitric oxide (NO) synthesis. In CBDL rats, macroscopic analysis demonstrated a 30% (P < .01) increase in cross-sectional area of the left ventricular (LV) wall without changes in the LV cavity or in the right ventricle (RV). Histomorphometric analysis revealed increased cell width (12%, P < .01) of cardiomyocytes from the LV of CBDL rats, but no differences in myocardial collagen content. Myocytes isolated from the LV were wider (12%) and longer (8%) than right ventricular myocytes (P < .01) in CBDL rats but not in controls. CBDL rats showed an increased expression of ANF and CK-B genes (P < .01). Isolated perfused CBDL hearts showed pressure/end-diastolic pressure curves and response to isoproterenol identical to sham hearts, although generated wall tension was reduced because of the increased wall thickness. Coronary resistance was markedly reduced. This reduction was abolished by inhibition of NO synthesis with N -nitro-L-arginine. Expression of eNOS was increased in CBDL hearts. In conclusion, portal hypertension associated to biliary cirrhosis induces marked LV hypertrophy and increased myocardial NO synthesis without detectable fibrosis or functional impairment. This observation could be relevant to patients with cirrhosis. [source]

Nitric Oxide: The "Second Messenger" of Insulin

IUBMB LIFE, Issue 5 2000
Nighat N. Kahn
Abstract Incubation of various tissues, including heart, liver, kidney, muscle, and intestine from mice and erythrocytes or their membrane fractions from humans, with physiologic concentration of insulin resulted in the activation of a membrane-bound nitric oxide synthase (NOS). Activation of NOS and synthesis of NO were stimulated by the binding of insulin to specific receptors on the cell surface. A Lineweaver-Burk plot of the enzymatic activity demonstrated that the stimulation of NOS by insulin was related to the decrease in the Km for L-arginine, the substrate for NOS, with a simultaneous increase of Vmax. Addition of NG-nitro-L-arginine methyl ester (LNAME), a competitive inhibitor of NOS, to the reaction mixture completely inhibited the hormone-stimulated NO synthesis in all tissues. Furthermore, NO had an insulin-like effect in stimulating glucose transport and glucose oxidation in muscle, a major site for insulin action. Addition of NAME to the reaction mixture completely blocked the stimulatory effect of insulin by inhibiting both NO production and glucose metabolism, without affecting the hormone-stimulated tyrosine or phosphatidylinositol 3-kinases of the membrane preparation. Injection of NO in alloxan-induced diabetic mice mimicked the effect of insulin in the control of hyperglycemia (i.e., lowered the glucose content in plasma). However, injection of NAME before the administration of insulin to diabetic-induced and nondiabetic mice inhibited not only the insulin-stimulated increase of NO in plasma but also the glucose-lowering effect of insulin. [source]

Nitric oxide and pain: ,Something old, something new'

Challenges have emerged following the revival of nitric oxide (NO) from ,something old', a simple gas derived from nitrogen and oxygen with a role in the early stages of evolution, into ,something new', an endogenously formed biological mediator regulating a wide variety of physiological functions. Although pain is a common sensation, it encompasses multiple neurobiologic components, of which NO is only one. In pain research, the study of NO is complicated by convoluted problems related mostly to the effects of NO, which are pro- or anti-nociceptive depending on the circumstances. This dual function reflects the multi-faceted roles of the NO molecule described in physiology. This review covers current information about NO and its implications in pain mechanisms. In addition, it follows the pain pathways, demonstrating the role of NO in peripheral nociceptive transmission as well in central sensitization. This knowledge may provide the scientific basis for developing new drugs that are indicated for different types of pain, drugs that may be related to the chemical links of NO. A comprehensive approach to understanding the effects of NO will help clinicians identify novel agents that combine the pharmacological profile of native drugs with a controllable manner of NO release. Inhibitors of NO synthesis may have analgesic effects and would be of interest for treating inflammatory and neuropathic pain. Unfortunately, only a few of these compounds have reached the stage of clinical pain trials. [source]

Aging Increases the Interleukin-1,,Induced INOS Gene Expression and Nitric Oxide (NO) Production in Vascular Smooth Muscle Cells

Gabriel HH Chan
Objectives: Inducible form of nitric oxide synthase (iNOS) is induced by cytokines (e.g. interleukin-1, (IL-1,)) during pathological conditions, such as sepsis. Excessive NO synthesis in blood vessels during sepsis can result in massive vasodilation and life-threatening hypotension. In addition, chronic expression of iNOS contributes to onset of diabetes, autoimmune diseases, arthritis, renal toxicity, and neurodegenerative disorders. The purpose of the present study was to examine the effect of aging on the levels of expression of iNOS induced by a low concentration (5 ng/ml) of IL-1, in VSMCs. Methods: Gene expression of iNOS was determined by RT-PCR and analysis of the PCR products by both agarose gel electrophoresis and capillary electrophoresis with laser-induced fluorescence detector (CE-LIF). This new CE-LIF technique, just developed in our laboratory, provides greater than 1,000 fold better sensitivity compared to agarose gels. The production of nitrite, the stable metabolite of NO, was measured (by a modified Griess reaction) in the media of cultured VSMCs isolated from young and elderly rats (3-month and 20-months old, respectively) of both genders following the exposure to IL-1, (5 ng/ml). VSMCs were used in their 1st passage to avoid phenotypic changes that typically occur in cultures of VSMCs after 3-10 passages. Results: IL-1, (5 ng/ml) caused a much larger increase in iNOS mRNA in VSMCs of elderly rats as compared to young rats. Furthermore, IL-1, (5 ng/ml) had no significant effect on nitrite levels in VSMCs of young, but significantly increased nitrite levels by 7.9 fold in VSMCs from elderly male rats and by 2.6 fold in VSMCs from elderly female rats, as compared to young rats. A report had previously shown that the neuropeptide CGRP could synergistically enhance the expression of iNOS caused by IL-1, in later passages (10-15 passages) of rat aortic VSMCs (i.e. phenotypically modulated VSMCs). We found that IL-1, and CGRP together did not act synergistically to increase production of nitrite in our phenotypically normal (1st passage) VSMCs. Conclusion: IL-1,, at a low concentration (5 ng/ml), preferentially induces iNOS expression and increases production of NO in VSMCs of elderly rats as compared to young rats. The data suggest that aging enhances the responsiveness of VSMCs to the iNOS-inducing actions of the cytokine IL-1,. This may be a contributing factor in the increased risk of developing severe hypotension in elderly patients with sepsis. (Supported by a Direct Grant for Research). [source]

AKT1 leader gene and downstream targets are involved in a rat model of kidney allograft tolerance,

Vojislav Jovanovic
Abstract Tolerance is the so-called "Holy Grail" of transplantation but achieving this state is proving a major challenge, particularly in the clinical settings. This tolerance state can be induced in rodent models using a variety of maneuvers. This phenomenon is classically characterized by donor specificity (recipients accept a secondary donor-specific allograft but reject third-party allograft) as well as by the absence of chronic rejection lesion. We previously showed that administration and anti-donor anti-class II serum on the day of transplantation induce tolerance to a kidney allograft in the LEW-1W to LEW-1A strain combination. In this study, we used DNA microarrays to compare gene patterns involved in anti-donor anti-class II tolerated or untreated syngeneic kidney transplants in this strain combination. Statistical and non-statistical analyses were combined with ab initio analysis, using the recently developed leader gene approach, to shed new light on this phenomenon. Theoretical and experimental results suggest that tolerance and rejection outcome may be in large part determined by low expression variations of some genes, which can form a core gene network around specific genes such as Rac1, NFKB1, RelA, AKT1, IKBKB, BCL2, BCLX, and CHUK. Through this model, we showed that AKT1 gene, WNT pathway and NO synthesis are strictly connected to each other and may play an important role in kidney tolerance and rejection processes, with AKT1 gene being the center of this complex network of interactions. J. Cell. Biochem. 111: 709,719, 2010. © 2010 Wiley-Liss, Inc. [source]

Nitric oxide synthesis inhibition alters rat cutaneous wound healing

Thaís P. Amadeu
Background:, Nitric oxide (NO) is an important molecule that participates in wound repair, but its effects on cutaneous wound healing are not well understood. The aim of this study was to investigate the effects of NO synthesis blockade on rat cutaneous wound healing by the administration of NG -nitro- l -arginine methyl ester (l -NAME), a non-selective inhibitor of NO synthases. Methods:, NO synthesis was inhibited by administration of l -NAME (20 mg/kg/day) in drinking water. An excisional wound was done, and the animals were killed 7, 14, and 21 days later. Wound contraction and blood pressure were evaluated. The lesion and adjacent skin were formalin fixed and paraffin embedded. Mast cells were quantified, and vessels were evaluated using stereological methods. Results:,l -NAME-treated animals presented delayed wound contraction, alterations in collagen organization, and neoepidermis thickness. The inhibition of NO synthesis increased mast cell migration 7 days after wounding, but decreased 21 days after wounding. Volume density of vessels was decreased in l -NAME-treated animals, 21 days after lesion. Surface density of vessels was frequently smaller in l -NAME-treated animals than in controls. Conclusion:, The blockade of NO synthesis impaired cutaneous wound healing, acting in early and late phases of wound repair. [source]

CAT2 arginine transporter deficiency significantly reduces iNOS-mediated NO production in astrocytes

Cathyryne K. Manner
Abstract We have previously demonstrated that genetic ablation of cationic amino acid transporter 2 (Cat2) significantly inhibits nitric oxide (NO) production by inducible nitric oxide synthase (iNOS) in activated macrophages. Here we report that iNOS activity is impaired by 84% in activated Cat2 -deficient astrocytes. Cat2 ablation appears to reduce astrocyte NO synthesis by decreasing the uptake of the sole precursor, arginine, as well as by reducing the expression of iNOS following activation. Excessive or dysregulated NO production by activated astrocytes and other CNS cell types has been implicated in the pathogenesis of neurological disorders. Our results support the idea that manipulation of CAT2 transporter function might be useful for the therapeutic modulation of iNOS activity. [source]

Manganese potentiates nuclear factor-,B-dependent expression of nitric oxide synthase 2 in astrocytes by activating soluble guanylate cyclase and extracellular responsive kinase signaling pathways

Julie A. Moreno
Abstract Inflammatory activation of glial cells is associated with neuronal injury in several degenerative movement disorders of the basal ganglia, including manganese neurotoxicity. Manganese (Mn) potentiates the effects of inflammatory cytokines on nuclear factor-,B (NF-,B)-dependent expression of nitric oxide synthase 2 (NOS2) in astrocytes, but the signaling mechanisms underlying this effect have remained elusive. It was postulated in the present studies that direct stimulation of cGMP synthesis and activation of mitogen-activated protein (MAP) kinase signaling pathways underlies the capacity of Mn to augment NF-,B-dependent gene expression in astrocytes. Exposure of primary cortical astrocytes to a low concentration of Mn (10 ,M) potentiated expression of NOS2 mRNA and protein along with production of NO in response to interferon-, (IFN,) and tumor necrosis factor-, (TNF,), which was prevented by overexpression of dominant negative I,B,. Mn also potentiated IFN,- and TNF,-induced phosphorylation of extracellular response kinase (ERK), p38, and JNK, as well as cytokine-induced activation of a fluorescent NF-,B reporter construct in transgenic astrocytes. Activation of ERK preceded that of NF-,B and was required for maximal activation of NO synthesis. Independently of IFN,/TNF,, Mn-stimulated synthesis of cGMP in astrocytes and inhibition of soluble guanylate cyclase (sGC) abolished the potentiating effect of Mn on MAP kinase phosphorylation, NF-,B activation, and production of NO. These data indicate that near-physiological concentrations of Mn potentiate cytokine-induced expression of NOS2 and production of NO in astrocytes via activation of sGC, which promotes ERK-dependent enhancement of NF-,B signaling. © 2008 Wiley-Liss, Inc. [source]

von Willebrand factor activates endothelial nitric oxide synthase in blood platelets by a glycoprotein Ib-dependent mechanism

Summary.,Background: The molecular regulation of endothelial nitric oxide synthase (eNOS) in blood platelets and the signalling events induced by platelet-derived NO are poorly defined. In particular, the ability of von Willebrand factor (VWF) to stimulate cyclic guanosine monophosphate (cGMP) formation in platelets has produced conflicting data. Objectives: To determine the mechanisms leading to eNOS activation and clarify the downstream signaling pathways activated by platelet-derived NO in response to VWF. Methods: We used three independent markers of NO signaling, [3H] l -citrulline production, cGMP accrual and immunoblotting of vasodilator,stimulated phosphoprotein (VASP) to examine the NO signaling cascade in response to VWF. Results: VWF increased NO synthesis and bioavailability, as evidenced by increased [3H] l -citrulline production and cGMP accrual, respectively. VWF-induced eNOS activation was GPIb-IX-dependent and independent of integrin ,IIb,3. cGMP formation in response to VWF required Ca2+ mobilization, Src family kinases, phosphatidylinositol 3-kinase and phospholipase C, but not protein kinase C. This suggests that a cross-talk between the signaling mechanisms regulates platelet activation and NO synthesis. VWF-induced cGMP accrual was completely blocked by apyrase and indomethacin, demonstrating an essential role for platelet-derived ADP and thromboxane A2 (TxA2). Elevated cGMP levels led to increased VASP phosphorylation at serine239 that was both protein kinase G (PKG)- and protein kinase A (PKA)-dependent. Conclusions: We demonstrate that VWF activates eNOS through a specific Ca2+ -dependent GPIb receptor-signaling cascade that relies on the generation of platelet-derived ADP and TxA2. Furthermore, we provide the first evidence to suggest that platelet derived-NO/cGMP activates PKA in addition to PKG. [source]

Acute remote ischemic preconditioning II: The role of nitric oxide

MICROSURGERY, Issue 6 2002
Markus V. Küntscher M.D.
The purpose of this study was to determine whether nitric oxide (NO) plays a role in the mechanism of acute "classic" as well as acute remote ischemic preconditioning (IP). Thirty-two male Wistar rats were divided into five experimental groups. The rat cremaster flap in vivo microscopy model was used for assessment of ischemia/reperfusion injury. In the control group (CG, n = 8), a 2-hr flap ischemia was induced after preparation of the cremaster muscle. The animals of group NO (n = 6) received 500 nmol/kg of the NO-donor spermine/nitric oxide complex (Sper/NO) intravenously 30 min prior to ischemia. The group LN + P (L-NAME + preclamping, n = 6) received 10 mg/kg N,-nitro-L-arginine methyl ester (L-NAME) intravenously before preclamping of the flap pedicle (10-min cycle length, 30-min reperfusion). L-NAME (10 mg/kg) was administered in group LN + T (L-NAME + tourniquet, n = 6) before ischemia of the right hindlimb was induced, using a tourniquet for 10 min after flap elevation. The limb was then reperfused for 30 min. Thereafter, flap ischemia was induced in each group as in group CG. In vivo microscopy was performed after 1 hr of flap reperfusion in each animal. Group NO demonstrated a significantly higher red blood cell velocity (RBV) in the first-order arterioles and capillaries, a higher capillary flow, and a decreased number of leukocytes adhering to the endothelium (stickers) of the postcapillary venules by comparison to all other groups (P < 0.05). The average capillary RBV and capillary flow were still higher in the CG than in the groups receiving L-NAME (P < 0.05). The data show that NO plays an important role in the mechanism of both acute "classic" as well as acute remote IP, since the administration of a NO-donor previous to ischemia simulates the effect of IP, whereas the nonspecific blocking of NO synthesis by L-NAME abolishes the protective effect of flap preconditioning. © 2002 Wiley-Liss, Inc. MICROSURGERY 22:227-231 2002 [source]

Nitric oxide synthesis and nitric oxide synthase expression in the kidney of rats treated by FK506

NEPHROLOGY, Issue 1 2002
SUMMARY: FK506-induced nephrotoxicity is characterized by a disturbance in renal haemody-namics that is attributed to an imbalance between the various modulators of renal vascular tone. It has not been well defined whether nitric oxide (NO), as an important vasoactive factor, is involved in FK506-induced nephrotoxicity. This study was designed to evaluate the involvement of nitric oxide in FK506-induced nephrotoxicity by investigating NO synthesis and NO synthase (NOS) expression in the kidney of rats treated with FK506. Male Wistar rats weighing 240,260 g, aged 11 weeks, were administered with FK506 (3.2mg/kg per day i.m.) for 4 weeks. Renal function and urinary NOx was measured using biochemical methods at the end of both 2 and 4 weeks of treatment. Expression of NOS protein and NOS mRNA in the kidney was also investigated using Western blot analysis and reverse transcription/polymerase chain reaction, respectively. FK506 administration induced nephrotoxicity, which was indicated by renal dysfunction (elevated blood urea nitrogen and creatinine, and reduced creatinine clearance, P < 0.05 vs control). FK506-induced nephrotoxicity was accompanied by higher urinary NOx excretion at the end of 2 weeks' treatment. In parallel with an increase in NO synthesis, increased eNOS protein and mRNA expression were also found in the renal medulla and renal cortex at week 2. the expression remained at higher levels in the renal medulla and returned to normal levels in the renal cortex at week 4. FK506 treatment induced nephrotoxicity in rats, which was accompanied by a temporal increase in NO synthesis in the kidney. Increased eNOS protein and mRNA expression were also found in the kidney of treated rats, which may be responsible for the enhanced NO synthesis. [source]

Plasma ADMA concentrations at birth and mechanical ventilation in preterm infants: A prospective pilot study

Milan C. Richir MD
Abstract Rationale Nitric oxide (NO) produced in the lung is an important mediator of normal lung development, vascular smooth muscle relaxation, and ventilation perfusion matching. NO is synthesized from arginine by the action of NO-synthase (NOS). Asymmetric dimethylarginine (ADMA), an endogenous derivate of arginine, inhibits NOS and is thereby a determinant of NO synthesis. We compared ADMA and arginine levels in preterm infants requiring mechanical ventilation with preterm infants who did not require mechanical ventilation and determined the relation between ADMA and the length of mechanical ventilation in these infants. Methods Thirty preterm infants, mean (SD) gestational age 29.3 (1.7) weeks and birth weight 1,340 (350) gram, of the Neonatal Intensive Care Unit of the VU University Medical Center were included. ADMA and arginine were measured in umbilical cord blood and the length of mechanical ventilation (days) was registered. Results Gestational age and birth weight were significantly smaller in infants requiring mechanical ventilation, but were not significantly correlated with plasma ADMA concentration after birth. Plasma ADMA concentrations were significantly higher in infants who required mechanical ventilation than in infants who did not require mechanical ventilation (1.53,±,0.23 and 1.37,±,0.14 µmol/L, respectively; P,=,0.036). ADMA concentration was significantly related to length of mechanical ventilation (B,=,3.4; 95% CI: 1.1,5.6; P,=,0.006), also after adjustment for gestational age (B,=,2.3; 95% CI: 0.4,4.2; P,=,0.024). Conclusions Preterm infants who require mechanical ventilation have increased ADMA levels compared to non-ventilated preterm infants. ADMA levels at birth are related to the length of mechanical ventilation. An increased ADMA concentration could reduce NO synthesis, which could lead to insufficient gas exchange and, consequently, a longer period of mechanical ventilation. Pediatr. Pulmonol. 2008; 43:1161,1166. © 2008 Wiley-Liss, Inc. [source]

Spontaneous labor increases nitric oxide synthesis during the early neonatal period

Akihiko Endo
AbstractBackground: This paper aimed to assess the influence of spontaneous labor upon endogenous nitric oxide (NO) and endothelin 1 (ET-1) during transition to extrauterine life. Methods: The serum levels of NO metabolites (the sum of nitrites and nitrates (NOx)) and the plasma level of ET-1 were determined in 53 healthy full-term infants (spontaneous labor group; n=40, cesarean delivery group; n=13). In both groups, blood samples were obtained from a cord vein at birth and from a peripheral vein at 5 days of age. Results: The differences in serum NOx concentrations between the spontaneous labor group and the elective cesarean group were not significant at birth. By the age of 5 days, serum NOx concentrations had risen significantly in the spontaneous labor group to become significantly higher in the elective cesarean group. Conclusion: It is speculated that spontaneous labor might enhance endogenous NO synthesis at 5 days of age. [source]

Suppressive effect of inducible nitric oxide synthase (iNOS) expression by the methanol extract of Actinodaphne lancifolia

Youngleem Kim
Abstract Nitric oxide (NO) produced by inducible nitric oxide synthase (iNOS) has played a crucial role in various pathophysiological processes including in,ammation and carcinogenesis. Therefore, the inhibitors of NO synthesis or iNOS gene expression have been considered as potential anti-in,ammatory and cancer chemopreventive agents. In our continuous search for iNOS inhibitors from natural products we have evaluated indigenous Korean plant extracts using an assay for inhibition of nitric oxide formation on lipopolysaccharide (LPS)-activated mouse macrophage RAW 264.7 cells. As a result, the methanolic stem extract of Actinodaphne lancifolia showed an inhibitory activity of NO production in a dose-dependent manner (IC50 = 2.5 µg/ml). Additional study demonstrated that the extract of Actinodaphne lancifolia signi,cantly suppressed the iNOS protein and gene expression in a dose-dependent manner. These results suggest that Actinodaphne lancifolia could be a potential candidate for developing an iNOS inhibitor from natural products. Further elucidation of active principles for development of new cancer chemopreventive and/or anti-in,ammatory agents could be warranted. Copyright © 2004 John Wiley & Sons, Ltd. [source]

Nitric oxide synthesis and signalling in plants

ABSTRACT As with all organisms, plants must respond to a plethora of external environmental cues. Individual plant cells must also perceive and respond to a wide range of internal signals. It is now well-accepted that nitric oxide (NO) is a component of the repertoire of signals that a plant uses to both thrive and survive. Recent experimental data have shown, or at least implicated, the involvement of NO in reproductive processes, control of development and in the regulation of physiological responses such as stomatal closure. However, although studies concerning NO synthesis and signalling in animals are well-advanced, in plants there are still fundamental questions concerning how NO is produced and used that need to be answered. For example, there is a range of potential NO-generating enzymes in plants, but no obvious plant nitric oxide synthase (NOS) homolog has yet been identified. Some studies have shown the importance of NOS-like enzymes in mediating NO responses in plants, while other studies suggest that the enzyme nitrate reductase (NR) is more important. Still, more published work suggests the involvement of completely different enzymes in plant NO synthesis. Similarly, it is not always clear how NO mediates its responses. Although it appears that in plants, as in animals, NO can lead to an increase in the signal cGMP which leads to altered ion channel activity and gene expression, it is not understood how this actually occurs. NO is a relatively reactive compound, and it is not always easy to study. Furthermore, its biological activity needs to be considered in conjunction with that of other compounds such as reactive oxygen species (ROS) which can have a profound effect on both its accumulation and function. In this paper, we will review the present understanding of how NO is produced in plants, how it is removed when its signal is no longer required and how it may be both perceived and acted upon. [source]

Prostaglandin F2, Stimulates Endothelial Nitric Oxide Synthase Depending on the Existence of Bovine Granulosa Cells: Analysis by Co-culture System of Endothelial Cells, Smooth Muscle Cells and Granulosa Cells

K Shirasuna
Contents Prostaglandin F2, (PGF2,) induces luteolysis in the mid but not in the early luteal phase; despite this, both the early and the mid corpus luteum (CL) have PGF2, receptor (FPr). We previously indicated that the luteal blood flow surrounding the CL drastically increases prior to a decrease of progesterone (P) in the cows, suggesting that an acute increase of luteal blood flow may be an early sign of luteolysis in response to PGF2, and that this may be induced by a vasorelaxant nitric oxide (NO). The aim of this study was to investigate the luteal stage-dependent and the site-restricted effect of PGF2, and NO on the mRNA expressions and P secretion. To mimic the local luteal region both of peripheral and central areas of the CL, we utilized co-cultures using bovine aorta endothelial cells (EC), smooth muscle cells (SMC) and luteinizing granulosa cells (GC) or fully-luteinized GC. PGF2, stimulated the expression of endothelial NO synthase (eNOS) mRNA at 0.5 h in mix-cultures of EC and SMC with fully-luteinized GC but not with luteinizing GC. The expression of eNOS mRNA in EC was increased by PGF2, at 1 h only when EC was cultured together with fully-luteinized GC but not with luteinizing GC. In all co-cultures, PGF2, did not affect the mRNA expression of FPr. Treatment of NO donor inhibited P secretion at 0.5 h. In conclusion, the present study suggests that the coexistence of the mature luteal cells (fully-luteinized GC) with EC/SMC may be crucial for acquiring functional NO synthesis induced by PGF2,. [source]

Effect of anion channel blockers on l- arginine action in spermatozoa from asthenospermic men

ANDROLOGIA, Issue 2 2010
S. Srivastava
Summary In earlier studies, we have established that l- arginine enhances motility and metabolic rate in spermatozoa of goat, bull and mouse. In the present study this work was extended to human sperm cells obtained from the semen samples of asthenospermic patients, which are characterised by low motility. The metabolic rate was followed by monitoring the glucose consumption (1- 13C glucose as substrate) and the production of lactate in sperm cells, using 13C NMR. The stimulatory effect of l- arginine was neutralised on adding an NO-synthase inhibitor like N, -nitro- l- arginine methyl ester. On the other hand, the inactive d -enantiomorph did not affect the stimulatory effect of l- arginine. This strongly suggests that l- arginine acts through the NO signal pathway. We also demonstrated that the stimulatory effect of l- arginine was inhibited in the presence of anion channel inhibitors like 4-acetamido-4,-isothiocyanostilbene-2,2,-disulphonic acid, 2,4-dinitrophenol and carbonyl cyanide m-chlorophenylhydrazone. Furthermore, bicarbonate supplementation was found to be essential for the action of l- arginine. These observations indicate that l- arginine induces NO synthesis and stimulates motility and metabolism only when an active anion transport system is present. [source]

A comparison of Ca2+ channel blocking mode between gabapentin and verapamil: implication for protection against hypoxic injury in rat cerebrocortical slices

Michiko Oka
The mode of Ca2+ channel blocking by gabapentin [1-(aminomethyl)cyclohexane acetic acid] was compared to those of other Ca2+ channel blockers, and the potential role of Ca2+ channel antagonists in providing protection against hypoxic injury was subsequently investigated in rat cerebrocortical slices. mRNA for the ,2, subunits of Ca2+ channels was found in rat cerebral cortex. Nitric oxide (NO) synthesis estimated from cGMP formation was enhanced by KCl stimulation, which was mediated primarily by the activation of N- and P/Q-type Ca2+ channels. Gabapentin blocked both types of Ca2+ channels, and preferentially reversed the response to 30 mM K+ stimulation compared with 50 mM K+ stimulation. In contrast, verapamil preferentially inhibited the response to depolarization by the higher concentration (50 mM) of K+. Gabapentin inhibited KCl-induced elevation of intracellular Ca2+ in primary neuronal culture. Hypoxic injury was induced in cerebrocortical slices by oxygen deprivation in the absence (severe injury) or presence of 3 mM glucose (mild injury). Gabapentin preferentially inhibited mild injury, while verapamil suppressed only severe injury. , -Conotoxin GVIA (, -CTX) and , -agatoxin IVA (, -Aga) were effective in both models. NO synthesis was enhanced in a manner dependent on the severity of hypoxic insults. Gabapentin reversed the NO synthesis induced by mild insults, while verapamil inhibited that elicited by severe insults. , -CTX and , -Aga were effective in both the cases. Therefore, the data suggest that gabapentin and verapamil cause activity-dependent Ca2+ channel blocking by different mechanisms, which are associated with their cerebroprotective actions and are dependent on the severity of hypoxic insults. British Journal of Pharmacology (2003) 139, 435,443. doi:10.1038/sj.bjp.0705246 [source]

Organ preservation solutions attenuate accumulation and nuclear translocation of hypoxia-inducible factor-1, in the hepatoma cell line HepG2

Renate Paddenberg
Abstract Hypoxia-inducible factor-1, (HIF-1,) is a key transcription factor orchestrating hypoxic and inflammatory reactions. Here, we determined the impact of organ preservation solutions (Celsior; histidine-tryptophan-ketoglutarate solution, HTK; University of Wisconsin solution; UW), oxygen supply, and temperature on HIF-1, accumulation, recorded by Western blotting and immunocytochemistry, in the human hepatoma cell line HepG2. Generation of reactive oxygen species (ROS), NO, and cell viability were concomitantly assessed. At 4°C, HIF-1, accumulation was not detectable. In normothermic (37°C) cell culture medium (Dulbecco's Modified Eagle's Medium, DMEM), HepG2 cells accumulated HIF-1, even in normoxia (21% O2) which was not observed in either of the preservation solutions. This correlated to high generation of NO, a normoxic stabilizer of HIF-1,, and L -arginine content (substrate for NO synthesis) in DMEM, and low NO production and absence of L -arginine in preservation solutions. In normothermic hypoxia up to 24,h, intracellular HIF-1, accumulated in all conditions, but less in preservation solutions compared to DMEM. The inhibitory effect on accumulation and nuclear translocation was most prominent for HTK, the only solution containing the activator of HIF-1, degradation, , -ketoglutarate. Addition of other intermediates of the tricarbon acid cycle,succinate, fumarate, malate,did not alter HIF-1, accumulation, although succinate exhibited a beneficial effect on cell viability in cold storage. In conclusion, preservation solutions attenuate accumulation and nuclear translocation of the transcription factor HIF-1,, and this property is seemingly related to their chemical composition (L -arginine, , -ketoglutarate). Thus, it appears feasible to design preservation solution specifically to modify HIF-1, accumulation and nuclear translocation. Copyright © 2009 John Wiley & Sons, Ltd. [source]

Hypertrophic pyloric stenosis and pulmonary hypertension in a neonate.

A common mechanism?
Abstract Nitric oxide (NO) is an important mediator of biological functions. Absence or shortage of NO plays a role in the pathogenesis of both hypertrophic pyloric stenosis and persistent pulmonary hypertension. We present a neonate diagnosed with pulmonary hypertension after birth caused by meconiumaspiration syndrome eventually treated with extracorporal membrane oxygenation followed by hypertrophic pyloric stenosis for which a pyloromyotomy was performed. In conclusion, the association of pulmonary hypertension and pyloric stenosis has not been described before and may be explained by a lowered plasma concentration of arginine leading to deficient NO synthesis in the affected organ systems. [source]

Heat stress increases endothelium-dependent relaxations and prevents reperfusion-induced endothelial dysfunction

Vincent Richard
Summary 1.,Heat stress has been widely used to stimulate the expression of stress proteins and is associated with various cardiovascular changes, including anti-ischaemic effects. However, the effect of heat stress on endothelial function is less clear. 2.,Heat stress was induced in anaesthetized rats by increasing body temperature to 42°C for 15 min. Twenty-four hours later, segments of rat aorta and mesenteric and coronary arteries were mounted in organ chambers. 3.,Heat stress markedly increased relaxation to acetylcholine (ACh) in all three blood vessels studied, without affecting the response to the nitric oxide (NO) donor sydnonimine-1. 4.,Heat stress also increased aortic relaxation to histamine and the calcium ionophore A23187. 5.,In the aorta, an inhibitor of NO synthesis abolished the response to ACh in both control and heat stressed-rings, whereas a cyclo-oxygenase inhibitor had no effect. 6.,Heat stress also prevented completely the impaired response to ACh in coronary arteries isolated from rats subjected to myocardial ischaemia and reperfusion. 7.,Thus, heat stress increases the stimulated release of NO the rat aorta and mesenteric and coronary arteries and prevents reperfusion-induced injury at the level of the coronary endothelium. [source]