Ethanol Induces Acute Pulmonary Vasoconstriction in Salt-Perfused Rat Lungs

Abstract

Ethanol is a pulmonary vasoconstrictor in rat lungs perfused in situ with Krebs-Henseleit salt solution. Pentobarbital-anesthetized rats were tracheotomized, and an in situ recirculating isolated lung perfusion was instituted using a Krebs-Henseleit buffer with 3% bovine albumin at 37^oC. Changes in pulmonary arterial pressure and tracheal inspiratory pressure during intravenous ethanol infusion at four different cumulative doses were measured in normoxic (n =6) and hyperoxic (n = 6) lungs, compared to normoxic perfusate (no ethanol infusion) controls (n = 6). Perfusate alcohol levels progressively increased in experimental groups. Perfusate gas and pH values were normal and not altered by ethanol. PAP increased by the end of ethanol infusion from 9.7 ± 2 to 26 ± 13 mm Hg in the normoxic group and from 10.6 to 22 ± 9 mm Hg in the hyperoxic lungs (p < .02); no change occurred in control lungs. Severe pulmonary edema occurred in 83% of the ethanol exposed lungs (vs. 0% of perfusate controls). Postethanol wet/dry weight ratios were twice normal (p < .02). Pulmonary arterial pressure rose in two stages. First there was a 25-100% increase before airway pressure increased, representing pulmonary vasoconstriction. This was followed by a precipitous 100-500% transmitted pressure rise as severe pulmonary edema developed. Thus, we conclude that the vasoconstrictor effect of ethanol on the pulmonary circulation occurs in rats as well as in lambs, dogs, and humans. In isolated perfused rat lungs, the response is locally mediated.