Journal of physiology and pharmacology : an official journal of the Polish Physiological Society
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J. Physiol. Pharmacol. · Jun 1997
Mediation by nitric oxide of the carbachol-induced corticosterone secretion in rats.
Nitric oxide synthase, an enzyme responsible for nitric oxide (NO) formation has been found in the hypothalamic paraventricular nucleus and median eminence, structures closely associated with regulation of the pituitary activity, and the pituitary gland itself. Nitric oxide modulates the stimulated release of CRH from the rat hypothalamus in vitro, which suggests its role in regulating the secretion of ACTH from the pituitary corticotrops and of corticosterone from the adrenal cortex. The purpose of the present study was to elucidate the yet unknown role of endogenous NO in the HPA response to central cholinergic stimulation in conscious rats. ⋯ L-NAME is a weak inhibitor of neuronal NOS itself, and must first be de-estrified to N omega-nitro-L-arginine to potently inhibit this enzyme. Systemic (10 mg/kg) and icv (1 microgram) pretreatment with L-NNA enhanced more effectively the carbachol-induced rise in corticosterone secretion than did pretreatment with L-NAME by either route. These results are the first direct evidence that endogenous NO significantly inhibits the HPA response to central cholinergic, muscarinic receptor stimulation under in vivo conditions.
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J. Physiol. Pharmacol. · Jun 1997
Clinical Trial Controlled Clinical TrialEndogenous nitric oxide in the control of esophageal motility in humans.
Recent animal studies have suggested that nitric oxide (NO) plays an important role in the regulation of esophageal motility, being partly responsible for latency period and latency gradient between the onset of a swallow and contractions of esophageal circular smooth muscles. The aim of this study was to evaluate whether endogenous NO is responsible for physiological timing of forthcoming contractions in the human esophageal body after swallowing. Eight male volunteers (age 21-25 years, weight 67-82 kg) were involved in this placebo controlled study on the effects of increasing doses of the NO synthase blocker, NG-monomethyl-L-arginine (L-NMMA 1.0-4.0 mumol/min i.v.), and/or L-arginine (L-arg) (30 mumol/kg-min i.v.) on the peristalsis of esophageal body in response to wet swallows (5 ml of water) and lower esophageal sphincter (LES) resting pressure. ⋯ The mean BP significantly increased during infusion of L-NMMA (control 97.0 +/- 5.7 vs. L-NMMA 4.0 mumol/min: 116.4 +/- 3.1 mm Hg) and this was also reversed by L-arg. We conclude that in humans endogenous NO is involved, at least in part, in the physiological regulation of motility patterns of the distal esophageal body and LES.