THE EFFECTS OF PHOTOACTIVATED PROTOPORPHYRIN ON RETICULOCYTE MEMBRANES, INTRACELLULAR ACTIVITIES and HEMOGLOBIN PRECIPITATION

Abstract— Photoactivated protoporphyrin effects were studied on reticulocyte membranes and distinct intracellular activities. Membrane bound (Na ₊ -K ₊)-ATPase activity and incorporation of ₅₅Fe into heme were almost 80% inhibited at a low concentration of protoporphyrin (3 fiM). On the other hand, a much higher protoporphyrin concentration (15 nM) was needed to cause 80% inhibition of protein synthesis. By 15 JXM protoporphyrin and treatment with light, an initial leak of hemoglobin out of the cells was observed. Electron microscopic examination showed that the lytic effects seem to be a result of membrane damage which appeared as holes in the membrane. Heinz-body-like particles of condensed hemoglobin were observed in the protoporphyrin-treated cells. The condensed hemoglobin spheres were shown to be bound to disrupted membranes prepared from photoactivated protoporphyrin-treated reticulocytes