Systemic and regional hemodynamics after nitric oxide synthase inhibition: role of a neurogenic mechanism.
The study tested the hypothesis that the increase in blood pressure and decrease in cardiac output after nitric oxide (NO) synthase inhibition with N omega-nitro-L-arginine methyl ester (L-NAME) was partially mediated by a neurogenic mechanism. Rats were anesthetized with Inactin (thiobutabarbital), and a control blood pressure was measured for 30 min. Cardiac output and tissue flows were measured with radioactive microspheres. All measurements of pressure and flows were made before and after NO synthase inhibition (20 mg/kg L-NAME) in a group of control animals and in a second group of animals in which the autonomic nervous system was blocked by 20 mg/kg hexamethonium. In this group of animals, an intravenous infusion of norepinephrine (20-140 ng/min) was used to maintain normal blood pressure. L-NAME treatment resulted in a significant increase in mean arterial pressure in both groups. L-NAME treatment decreased cardiac output approximately 50% in both the intact and autonomic blocked animals (P < 0.05). Autonomic blockade alone had no effect on tissue flows. L-NAME treatment caused a significant decrease in renal, hepatic artery, stomach, intestinal, and testicular blood flow in both groups. These results demonstrate that the increase in blood pressure and decreases in cardiac output and tissue flows after L-NAME treatment are not dependent on a neurogenic mechanism.
Huang
M
M
Department of Physiology and Pediatrics, University of Mississippi Medical Center, Jackson 39216-4505.
Leblanc
M L
ML
Hester
R L
RL
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001341:Autonomic Nervous System / Q000502:physiology*; D005730:Ganglionic Blockers / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D019001:Nitric Oxide Synthase; D051381:Rats; D017207:Rats, Sprague-Dawley; D012039:Regional Blood Flow / Q000187:drug effects
D005730:Ganglionic Blockers; D006584:Hexamethonium Compounds; D018738:Hexamethonium; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D019331:NG-Nitroarginine Methyl Ester