scholarly journals Vasoactivity of adenosine in the trout (Oncorhynchus mykiss) coronary system: involvement of nitric oxide and interaction with noradrenaline

1998 ◽  
Vol 201 (22) ◽  
pp. 3075-3083 ◽  
Author(s):  
T Mustafa ◽  
C Agnisola
Keyword(s):  
Nitric Oxide ◽  
Constant Pressure ◽  
Constant Flow ◽  
Nitric Oxide Synthase Inhibitor ◽  
Heart Preparation ◽  
Synthase Inhibitor ◽  
Coronary Endothelium ◽  
Oxide Synthase ◽  
Working Heart

A vasoconstrictory response to adenosine has been reported in coronary rings from fish. Since the reactivity of the large coronary arteries and the microcirculation may differ, the present study was undertaken to determine the role of adenosine in the intact coronary system of trout under constant pressure or flow using an isolated and non-working heart preparation. The involvement of nitric oxide (NO) and the interaction with noradrenaline were also studied. At 10(-9) to 10(-8 )mol l-1, adenosine caused a vasoconstrictory response, whereas between 10(-7) and 10(-5 )mol l-1 the response was predominantly vasodilative. Theophylline abolished both these responses to adenosine. The vasodilation induced by adenosine (at 10(-5 )mol l-1) was significantly reduced when the preparation was perfused under constant-flow than rather under constant-pressure conditions. The nitric oxide synthase inhibitor N-nitro-l-arginine (l-NA, 10(-4 )mol l-1) partially reduced the vasodilation induced by adenosine (at 10(-5 )mol l-1) under constant-pressure but not under constant-flow conditions. Perfusion of the intact coronary system with l-arginine or with adenosine significantly increased the rate of nitrite (NO2-) release, while perfusion with l-NA or theophylline reduced NO2- release. Chemical denudation of the coronary endothelium by CHAPS resulted in the loss of both the l-arginine- and adenosine-mediated vasodilation and the l-arginine-induced increase in the rate of NO2- release. Adenosine (10(-5 )mol l-1) offset and overrode the vasoconstriction induced by 10(-7 )mol l-1 noradrenaline. l-NA inhibited only the adenosine-induced vasodilation but not the ability to offset noradrenaline vasoconstriction, excluding the involvement of NO in the interaction between adenosine and noradrenaline.

scholarly journals Cardiac sympathetic afferent stimulation by bradykinin in heart failure: role of NO and prostaglandins

1998 ◽  
Vol 275 (3) ◽  
pp. H783-H788 ◽  
Author(s):  
Wei Wang
Keyword(s):  
Nitric Oxide ◽  
Heart Failure ◽  
Large Degree ◽  
Afferent Stimulation ◽  
Nitric Oxide Synthase Inhibitor ◽  
Renal Sympathetic Nerve Activity ◽  
Significant Change ◽  
Synthase Inhibitor ◽  
Oxide Synthase

I have shown that cardiac sympathetic afferent stimulation by epicardial application of bradykinin (BK) was significantly enhanced in pacing-induced heart failure (HF) dogs. This enhancement appeared to be mediated by prostaglandins. The present study was to determine whether nitric oxide is involved in this enhancement. Under α-chloralose (100 mg/kg iv) anesthesia, the renal sympathetic nerve activity (RSNA) response to BK was determined in 15 HF and 15 sham dogs in the sinoaortic-denervated and vagotomized state. The RSNA response to BK was significantly enhanced in HF. This enhanced RSNA response to BK was significantly reduced in the HF dogs after administration of the cycloxygenase inhibitor indomethacin (5 mg/kg iv), but no significant change was found in the sham group. In contrast, RSNA responses to BK were significantly reduced in the sham dogs after administration of the nitric oxide synthase inhibitor N G-nitro-l-arginine methyl ester (l-NAME, 30 mg/kg iv), but no significant change was found in the HF group. These data suggest that the RSNA response to BK is mediated by nitric oxide to a large degree in the normal state but is primarily mediated by prostaglandins in the HF state.

scholarly journals Augmented central nitric oxide production inhibits vasopressin release during hemorrhage in acute alcohol-intoxicated rodents

2011 ◽  
Vol 301 (5) ◽  
pp. R1529-R1539 ◽  
Author(s):  
Annie M. Whitaker ◽  
Jesse K. Sulzer ◽  
Patricia E. Molina
Keyword(s):  
Nitric Oxide ◽  
Alcohol Intoxication ◽  
Sprague Dawley ◽  
Nitric Oxide Synthase Inhibitor ◽  
Vasopressin Release ◽  
No Inhibition ◽  
Sprague Dawley Rats ◽  
Synthase Inhibitor ◽  
Oxide Synthase

Acute alcohol intoxication (AAI) attenuates the AVP response to hemorrhage, contributing to impaired hemodynamic counter-regulation. This can be restored by central cholinergic stimulation, implicating disrupted signaling regulating AVP release. AVP is released in response to hemorrhage and hyperosmolality. Studies have demonstrated nitric oxide (NO) to play an inhibitory role on AVP release. AAI has been shown to increase NO content in the paraventricular nucleus. We hypothesized that the attenuated AVP response to hemorrhage during AAI is the result of increased central NO inhibition. In addition, we predicted that the increased NO tone during AAI would impair the AVP response to hyperosmolality. Conscious male Sprague-Dawley rats (300–325 g) received a 15-h intragastric infusion of alcohol (2.5 g/kg + 300 mg·kg−1·h−1) or dextrose prior to a 60-min fixed-pressure hemorrhage (∼40 mmHg) or 5% hypertonic saline infusion (0.05 ml·kg−1·min−1). AAI attenuated the AVP response to hemorrhage, which was associated with increased paraventricular NO content. In contrast, AAI did not impair the AVP response to hyperosmolality. This was accompanied by decreased paraventricular NO content. To confirm the role of NO in the alcohol-induced inhibition of AVP release during hemorrhage, the nitric oxide synthase inhibitor, nitro-l-arginine methyl ester (l-NAME; 250 μg/5 μl), was administered centrally prior to hemorrhage. l-NAME did not further increase AVP levels during hemorrhage in dextrose-treated animals; however, it restored the AVP response during AAI. These results indicate that AAI impairs the AVP response to hemorrhage, while not affecting the response to hyperosmolality. Furthermore, these data demonstrate that the attenuated AVP response to hemorrhage is the result of augmented central NO inhibition.

Role of nitric oxide during hyperventilation-induced bronchoconstriction in the guinea pig

2001 ◽  
Vol 90 (4) ◽  
pp. 1474-1480 ◽  
Author(s):  
Oscar E. Suman ◽  
Kenneth C. Beck
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Respiratory Rate ◽  
Guinea Pigs ◽  
Nitric Oxide Synthase Inhibitor ◽  
Airway Function ◽  
Respiratory System Resistance ◽  
Synthase Inhibitor ◽  
Oxide Synthase

Airway function is largely preserved during exercise or isocapnic hyperventilation in humans and guinea pigs despite likely changes in airway milieu during hyperpnea. It is only on cessation of a hyperpneic challenge that airway function deteriorates significantly. We tested the hypothesis that nitric oxide, a known bronchodilator that is produced in the lungs and bronchi, might be responsible for the relative bronchodilation observed during hyperventilation (HV) in guinea pigs. Three groups of anesthetized guinea pigs were given saline and three groups given 50 mg/kg N G-monomethyl-l-arginine (l-NMMA), a potent nitric oxide synthase inhibitor. Three isocapnic ventilation groups included normal ventilation [40 breaths/min, 6 ml/kg tidal volume (Vt)], increased respiratory rate only (150 breaths/min, 6 ml/kg Vt), and increased respiratory rate and increased volume (100 breaths/min, 8 ml/kg Vt). l-NMMA reduced expired nitric oxide in all groups. Expired nitric oxide was slightly but significantly increased by HV in the saline groups. However, inhibition of nitric oxide production had no significant effect on rate of rise of respiratory system resistance (Rrs) during HV or on the larger rise in Rrs seen 6 min after HV. We conclude that nitric oxide synthase inhibition has no effect on changes in Rrs, either during or after HV in guinea pigs.

Role of nitric oxide in methacholine-induced sweating and vasodilation in human skin

2006 ◽  
Vol 100 (4) ◽  
pp. 1355-1360 ◽  
Author(s):  
Kichang Lee ◽  
Gary W. Mack
Keyword(s):  
Nitric Oxide ◽  
Nitric Oxide Synthase ◽  
Muscarinic Receptor ◽  
Human Skin ◽  
Sweat Rate ◽  
Microdialysis Probe ◽  
Nitric Oxide Synthase Inhibitor ◽  
Synthase Inhibitor ◽  
Oxide Synthase

The purpose of this study was to determine whether the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME) demonstrates significant muscarinic-receptor antagonism during methacholine (MCh)-stimulated sweating in human forearm skin. Three intradermal microdialysis probes were placed in the skin of eight healthy adults (4 men and 4 women). MCh in the range of 0.033–243 mM in nine steps was perfused through a microdialysis probe with and without the presence of the nitric oxide synthase inhibitor l-NAME (10 mM) or the l-arginine analog NG-monomethyl-l-arginine (l-NMMA; 10 mM). Local sweat rate (sweat rate) and skin blood flow (laser-Doppler velocimetry) were measured directly over each microdialysis probe. We observed similar resting sweat rates at MCh only, MCh and l-NAME, and MCh and l-NMMA sites averaging 0.175 ± 0.029, 0.186 ± 0.034, and 0.139 ± 0.027 mg·min−1·cm−2, respectively. Peak sweat rate (0.46 ± 0.11, 0.56 ± 0.16, and 0.53 ± 0.16. mg·min−1·cm−2) was also similar among all three sites. MCh produced a sigmoid-shape dose-response curve and 50% of the maximal attainable response (0.42 ± 0.14 mM for MCh only) was shifted rightward shift in the presence of l-NAME or l-NMMA (2.88 ± 0.79 and 3.91 ± 1.14 mM, respectively; P < 0.05). These results indicate that nitric oxide acts to augment MCh-stimulated sweat gland function in human skin. In addition, l-NAME consistently blunted the MCh-induced vasodilation, whereas l-NMMA did not. These data support the hypothesis that muscarinic-induced dilation in cutaneous blood vessels is not mediated by nitric oxide production and that the role of l-NAME in attenuating acetylcholine-induced vasodilation may be due to its potential to act as a muscarinic-receptor antagonist.

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