Augmentation of hypoxic pulmonary vasoconstriction by N(G)-L-methyl-arginine in a rabbit model of thermal injury.
We tested deeply anesthetized rabbits to determine if a burn acutely diminished the strength of hypoxic pulmonary vasoconstriction (HPV) and if this could be augmented by L-NMMA, a nitric oxide synthase inhibitor. We induced a burn using water heated to 75 degrees C and assessed the strength of HPV as the difference in pulmonary vascular resistance during 100% and 13% O2 ventilation. The rabbits then were randomized to receive 10 mg/kg L-NMMA (n = 8) or a placebo (n = 8). The strength of HPV decreased from 0.42 +/- 0.11 mm Hg/mL/min preburn to 0.22 +/- 0.11 mm Hg/mL/min postburn (P <.05). L-NMMA administration augmented HPV to a postburn value of 0.48 +/- 0.014 mm Hg/mL/min (P <.05). We speculate that the loss of HPV following a burn could worsen ventilation to perfusion mismatch and thereby aggravate the hypoxia associated with burns. Augmentation of HPV might be a short-term goal during the acute stabilization of hypoxic burn patients.
Department of Medicine, University of Alberta, Edmonton, Canada.
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Mayers
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Hurst
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Johnson
D000818:Animals; D002056:Burns / Q000503:physiopathology*; D004195:Disease Models, Animal; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006439:Hemodynamics / Q000187:drug effects; D000860:Hypoxia / Q000503:physiopathology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D011651:Pulmonary Artery / Q000187:drug effects / Q000503:physiopathology*; D011817:Rabbits; D014661:Vasoconstriction / Q000187:drug effects*; D019323:omega-N-Methylarginine / Q000494:pharmacology*
D004791:Enzyme Inhibitors; D019323:omega-N-Methylarginine; D019001:Nitric Oxide Synthase