Studies Based on Biophysical Chemistry on the Mechanisms of Modification of Platelet Functions by Membrane Reactive Compounds

Abstract

Physico-chemical properties of the blood platelets and their membrane were investigated by fluorescence analysis and electron spin resonance spectrometry. Fluorescence analysis using diphenylhexatriene and its ionic derivatives revealed that the inner membrane compartment of the platelets is more fluid than the outer layer of the plasma membrane. Further, the relationship between the increase in membrane fluidity by membrane reactive compounds such as alcohols and their inhibitory effects on platelet function was clarified. These compounds seem to inhibit platelet function due to stimulation of adenylate cyclase, which is mediated by perturbation of the central region of the membrane lipid bilayer. The effects of monovalent cations and anions on platelet function was also examined and their mechanisms were studied. It was indicated that monovalent cations such as alkali metal cations modify platelet aggregation by changing fibrinogen binding. On the other hand, monovalent anions modified platelet function by quite different mechanism. Furthermore, generation of hydroxyl radicals by platelets and its enhancement accompanied with the activation of platelets were revealed. It was inhibited by inhibitors of platelet activation such as forskolin and phenolic antioxidants.