Effects of an inhibitor of angiotensin converting enzyme (Captopril) on pulmonary and renal insufficiency due to intravascular coagulation in the rat.

Induction of intravascular coagulation and inhibition of fibrinolysis by injection of thrombin and tranexamic acid (AMCA) in the rat gives rise to pulmonary and renal insufficiency resembling that occurring after trauma or sepsis in man. Injection of Captopril (1 mg/kg), an inhibitor of angiotensin converting enzyme (ACE), reduced both pulmonary and renal insufficiency in this rat model. The lung weights were lower and PaO2 was improved in rats given this enzyme-blocking agent. The contents of albumin in the lungs were not changed, indicating that Captopril did not influence the extravasation of protein. Renal damage as reflected by an increase in serum urea and in kidney weight was prevented by Captopril. The amount of fibrin in the kidneys was also considerably lower than in animals which received thrombin and AMCA alone. It is suggested that the effects of Captopril on the lungs may be attributable to a vasodilatory effect due to a reduction in the circulating level of Angiotension II and an increase in prostacyclin (secondary to an increase in bradykinin). Captopril may, by the same mechanism, reduce the increase in glomerular filtration that is known to occur after an injection of thrombin, thereby diminishing the aggregation of fibrin monomers in the glomeruli, with the result that less fibrin will be deposited and thus less kidney damage will be produced.