EXTRA-PULMONARY EFFECTS OF INHALED NITRIC-OXIDE IN SWINE WITH AND WITHOUT PHENYLEPHRINE

We have compared the effects of inhaled nitric oxide (iNO) and i.v. ni troglycerin (ivGTN) on the haemodynamic response to phenylephrine-indu ced hypertension (PEHT) in anaesthetized pigs. PEHT did not change eit her pulmonary vascular resistance or gas exchange throughout all exper iments. Both treatments lowered pulmonary arterial pressure to the sam e extent (-12.4% iNO; -13.7% ivGTN) and passively via an effect on lef t atrial pressure (-26.3% iNO; -31.4% ivGTN). Both treatments failed t o reverse the decrease in renal blood flow (RBFc) induced by PEHT, but both increased urinary flow (UF) (+128% iNO; +148% ivGTN). IvGTN sign ificantly increased plasma concentrations of nitrite and nitrate durin g (+22.7% arterial blood; +26.2% venous blood) and beyond the period o f infusion (iNO: +6.4% and +4.9%, respectively). In four control pigs (no PEHT), iNO markedly increased RBFc (+109%), glomerular filtration rate (1-72.5%) and UF (+68.7%). We conclude that iNO may have direct c ardiac and renal effects, probably via intervention of NO carrier form s such as S-nitroso compounds.