NG-methylarginine, an inhibitor of endothelium-derived nitric oxide synthesis, is a potent pressor agent in the guinea pig: does nitric oxide regulate blood pressure in vivo?
Nitric oxide is a major endothelium-derived vascular smooth muscle relaxing factor; its synthesis from L-arginine is selectively inhibited by L-NG-methylarginine. To assess whether basal nitric oxide release contributes to blood pressure regulation in vivo, we have investigated the cardiovascular effects of L-NG-methylarginine in the anesthetized guinea pig. L-NG-methylarginine (0.1-10 mg/kg, i.v. bolus) elicited a sustained, dose-dependent, increase in arterial pressure and a moderate bradycardia. L-arginine (30 mg/kg i.v.) prevented or reversed the pressor effect of L-NG-methylarginine, while atropine (2 mg/kg) abolished the associated bradycardia. In contrast, L-arginine did not attenuate the pressor effect of norepinephrine or angiotensin. Our findings suggest that basal nitric oxide production is sufficient to modulate peripheral vascular resistance; hence nitric oxide may play a role in arterial pressure homeostasis.
Aisaka
K
K
Department of Pharmacology, Cornell University Medical College, New York 10021.
Gross
S S
SS
Griffith
O W
OW
Levi
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R
D000804:Angiotensin II / Q000008:administration & dosage; D000818:Animals; D001120:Arginine / Q000008:administration & dosage / Q000031:analogs & derivatives*; D001794:Blood Pressure / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000502:physiology*; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D007275:Injections, Intravenous; D008297:Male; D009569:Nitric Oxide / Q000096:biosynthesis / Q000502:physiology*; D009638:Norepinephrine / Q000008:administration & dosage; D011292:Premedication; D014662:Vasoconstrictor Agents / Q000008:administration & dosage*; D019323:omega-N-Methylarginine
D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine; D009638:Norepinephrine