Action of salicylate on failing heart lung preparations of guinea-pig perfused with red blood cells suspended in Tyrode-dextrane.

Heart lung preparations (HLP) of guinea-pig were perfused with homologous red blood cells suspended in 1.5 volumes of Tyrode containing 6% dextrane. Red blood cells were freshly obtained by centrifugation of heparinized blood and subsequent washing with saline. Reduced pulmonary expansion due to bronchoconstriction, increased pulmonary vascular resistance and heart failure rapidly occurred in these preparations. Addition of salicylate to the perfusing medium delayed and attenuated both the respiratory and the cardiac disturbances. A full protection against cardiopulmonary failure was obtained when salicylate was added to the heparinized blood used for red blood cells preparation and to the saline used for red blood cells washing. It is concluded that pulmonary microembolism, due to platelet aggregation, is the primary factor responsible for HLP failure. Bronchoconstriction and pulmonary vasoconstriction are aggravating factors secondary to microembolism. Salicylate appears to prevent the microembolism and the microembolism depending release of broncho- and vaso-constrictor autacoids.