Alamethicin-induced pore formation in biological membranes.

The effects of alamethicin on the membrane barrier function of rabbit erythrocytes, human platelets and sarcoplasmic reticulum vesicles, as well as on that of brain microsomes and liver mitochondria of the rat were compared. An upset of the barrier function was observed for plasma membranes of brain microsomes as well as for erythrocyte and platelet membranes at alamethicin concentrations ranging between 25-80 micrograms/ml. The membrane barrier functions of sarcoplasmic reticulum vesicles, of endoplasmic reticulum vesicles of rat brain microsomes, and of liver mitochondria were disturbed at 3-7 micrograms/ml alamethicin. The different sensitivities of plasma and intracellular membranes to alamethicin were supposed to be due to the presence of considerable quantities of cholesterol in plasma membranes as well as to peculiarities of their protein compositions.