title: Inhibition of nitric oxide synthesis potentiates hypoxic vasoconstriction in isolated rat lungs.
abstract: We have investigated the influence of endogenous nitric oxide (NO) on the vascular resistance of isolated rat lungs by inhibiting its synthesis with the false substrate N-monomethyl-L-arginine (L-NMMA). When perfused with blood at constant flow the addition of L-NMMA (10(-3) M) did not affect pulmonary arterial pressure in hyperoxia but did increase the response to hypoxia (PO2 25-35 mmHg) by 2.5 +/- 0.2 fold (mean +/- S.E.M.). The effect of L-NMMA was reversed by 3 x 10(-3) M-L-arginine, the true substrate for NO synthesis. Thus NO is an important pulmonary vasodilator but hypoxic vasoconstriction does not result from a reduction of its background release.
authors.affiliation: University Laboratory of Physiology, Oxford.
authors.forename: B E
authors.initials: BE
authors.lastname: Robertson
authors.forename: J B
authors.initials: JB
authors.lastname: Warren
authors.forename: P C
authors.initials: PC
authors.lastname: Nye
mesh_terms: D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000860:Hypoxia / Q000378:metabolism; D008297:Male; D009569:Nitric Oxide / Q000037:antagonists & inhibitors; D011652:Pulmonary Circulation / Q000187:drug effects / Q000502:physiology*; D011669:Pulmonary Wedge Pressure / Q000187:drug effects / Q000502:physiology; D051381:Rats; D014661:Vasoconstriction / Q000187:drug effects / Q000502:physiology*; D019323:omega-N-Methylarginine
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D001120:Arginine