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 d iminished the strength of hypoxic pulmonary vasoconstriction (HPV) and if this could be augmented by L-NMMA, a nitric oxide synthase inhibit or, 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% O-2 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 s peculate that the loss of HPV following a burn could worsen ventilatio n to perfusion mismatch and thereby aggravate the hypoxia associated w ith burns, Augmentation of HPV might be a short term goal during the a cute stabilization of hypoxic burn patients. Copyright (C) 1996 by W.B . Saunders Company