[Role of calcium ions and fatty acids in the inhibition of Mg2+, Na+ and K+-ATPases by means of the "direct" hemolysin and phospholipase A of cobra venom].

The influence of calcium ions and fatty acids in the action of direct hemolytic factor and phospholipase A on Mg2+ and Na+, K+-ATPases was investigated. It was established that calcium activates greatly phospholipase A and to a less extent--the direct hemolytic factor. The activity of ATPases is inhibited most effectively by the system consisting of phospholipase A, direct hemolytic factor and Ca2+. Fatty acids can participate in the mechanism of membrane ATPases inhibition.