Role of nitric oxide in vasopressinergic pulmonary vasodilatation.
Experiments were performed to determine the mechanism of vasopressinergic pulmonary vasodilation in isolated, salt-perfused rat lungs. Administration of a 50-ng bolus of arginine vasopressin (AVP) to lungs preconstricted with the synthetic thromboxane analogue U-46619 resulted in a 66% reversal of pulmonary vasoconstriction. Administration of the known endothelium-dependent vasodilator ATP resulted in a parallel decrease in pressure. The vasodilatory responses to both agents were significantly attenuated by pretreatment with the nitric oxide synthesis inhibitor N omega-nitro-L-arginine (L-NNA). In addition to attenuating the vasodilatory response to these agents, L-NNA pretreatment caused a significant augmentation of the pressor response to U-46619 without affecting baseline pulmonary arterial pressure. The attenuation of vasopressinergic pulmonary vasodilation by L-NNA was completely reversed by addition of excess substrate for NO production (50 mM L-arginine) but was unaffected by addition of equimolar amounts of D-arginine. Finally, L-NNA pretreatment failed to attenuate the vasodilatory actions of sodium nitroprusside and isoproterenol. We conclude that AVP dilates the preconstricted pulmonary vasculature via the release of nitric oxide.
Russ
R D
RD
Department of Physiology, University of New Mexico School of Medicine, Albuquerque 87131.
Walker
B R
BR
D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D001127:Arginine Vasopressin / Q000494:pharmacology*; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D009569:Nitric Oxide / Q000378:metabolism*; D019335:Nitroarginine; D010477:Perfusion / Q000379:methods; D011450:Prostaglandin Endoperoxides, Synthetic / Q000494:pharmacology; D011651:Pulmonary Artery / Q000502:physiology; D011652:Pulmonary Circulation / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D014661:Vasoconstriction / Q000187:drug effects; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology*
D011450:Prostaglandin Endoperoxides, Synthetic; D001127:Arginine Vasopressin; D019335:Nitroarginine; D009569:Nitric Oxide; D019796:15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5,13-dienoic Acid; D001120:Arginine; D007545:Isoproterenol