Ca2+ and the interaction of pore-formers with membranes

The interaction of pore-forming agents, such as Sendai virus, influenza virus (at pH 5 3), activated complement,Staphylococcus aureus α-toxin, melittin and polylysine, with the surface membrane of cells has been studied. In each case the following changes are initiated: collapse of membrane potential, leakage of ions, and leakage of phosphorylated metabolites. The changes can be inihibited by extracellular Ca²⁺ at physiological concentration; Mg²⁺ is less effective, and Zn²⁺ is more effective, than Ca²⁺ Ca²⁺ appears to act at a stage subsequent to the binding of pore-forming agent to cells. It is concluded that divalent cations are able to protect cells against the damaging effects of certain viruses, toxins or the components of activated complement in a manner that is worthy of further investigation.