Inhalation of a nitric oxide synthase inhibitor to a hypoxic or collapsed lung lobe in anaesthetized pigs: effects on pulmonary blood flow distribution.
I.v. administration of the nitric oxide synthase inhibitor, nitro-L-arginine methyl ester (L-NAME), not only reduces blood flow in a hypoxic lung region but also causes systemic vasoconstriction and a decrease in cardiac output. In this study, we delivered nebulized L-NAME 0.2-1 mg kg-1 to the left lower lobe of 10 anaesthetized pigs. The left lower lobe was made hypoxic by selective inhalation of 5% oxygen or collapsed by interrupted ventilation, or both. Inhalation of L-NAME reduced fractional blood flow to the left lower lobe from 5.3 (SD 3.1)% to 1.7 (1.4)% (P < 0.05) in lobar hypoxia and from 6.0 (3.3) to 2.7 (2.7)% (P < 0.05) in lobar collapse. These reductions were accompanied by a significant increase in PaO2. There were no significant changes in arterial pressure, cardiac output or heart rate. We have shown that selective inhalation of L-NAME reduced blood flow to a hypoxic or collapsed lung region without systemic effects. The possible role for nitric oxide synthase inhibition in reducing shunt during one-lung ventilation, however, requires further study.
Fredén
F
F
Department of Anaesthesiology and Intensive Care, Uppsala University Hospital, Sweden.
Berglund
J E
JE
Reber
A
A
Högman
M
M
Hedenstierna
G
G
D000280:Administration, Inhalation; D000818:Animals; D001120:Arginine / Q000494:pharmacology; D006439:Hemodynamics / Q000187:drug effects; D000860:Hypoxia / Q000503:physiopathology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D011652:Pulmonary Circulation / Q000187:drug effects*; D013552:Swine
D001120:Arginine; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester