Influence of charge and molecular size on membrane stabilization.

We have reported that the antihaemolytic effect of low concentrations of chlorpromazine is decreased after enzymic removal of sialopeptides from red cell membranes, suggesting that an interaction between negatively charged sialic acids and positively charged chlorpromazine is involved in its membrane stabilizing effect. We have now investigated the antihaemolytic action of simpler molecules with different charges Removal of membrane sialopeptides did not affect the membrane stabilizing actions of simple aliphatic mono- or diamines nor of similar aliphatic molecules carrying strong positive or negative charges, where those positively charged were more potent than those with negative charges. It appears, therefore, that membrane stabilizing activity is determined primarily by lipophilicity and secondarily by polarity and that it does not depend on interactions with enzymically accessible sialopeptides on the outer surface of biological membranes.