Pulmonary vasoconstriction produced by protamine and protamine-heparin complex in the isolated cat lung perfused with blood or dextran.

Injections of protamine sulphate, protamine-heparin complex, and the supernatant from this mixture produced a rise in pulmonary artery pressure during constant flow perfusion in the isolated cat lung. The rise in pressure occurred with both blood and dextran perfusates. This suggests that the pulmonary vasoconstriction produced by protamine may be partly due to a direct action on the pulmonary vasculature or to the release of vasoactive substances from the lungs.