The effect of hematoporphyrin and light on human platelets. III. Release of potassium and acid phosphatase

Human platelets, exposed to hematoporphyrin and light, were depleted of potassium and acid phosphatase. A linear relationship was demonstrated between the per cent depletion of potassium from irradiated platelets and the log dose of hematoporphyrin. The initial release of potassium and acid phosphatase from irradiated platelets was first order. Rate constants demonstrated that potassium was released five times faster than acid phosphatase. At 4°C, release of both potassium and acid phosphatase was the same as at 37°C. These results are compared to previous data on the release of serotonin from irradiated platelets.