Effects of exogenous phospholipases on brain membrane phospholipid perturbation, (Na(+) + K(+))-ATPase activity and cellular swelling of brain slices.

Rat brain membranes were incubated with bee venom phospholipase A(2) (PLA(2)) or phospholipase C (PLC) from Clostridium perfringens. PLA(2) caused a significant increase in free polyunsaturated fatty acids concomitant with membrane phospholipid degradation as monitored by HPLC and by gas chromatography. Equal concentrations of PLC had a much lesser effect than PLA(2). Divergent and differential effects were shown on deacylation and incorporation of [(3)H]arachidonic acid in membrane phospholipids. The incorporation of [(3)H]arachidonic acid into various phospholipids was greatly reduced by PLA(2) (0.018 units/ml) whereas PLC at identical concentration was not effective. PLA(2) inhibited (Na(+) + K(+))-ATPase but was not effective on p-nitrophenyl-phosphatase activity whereas PLC stimulated both enzymes. PLA(2) induced swelling of cortical brain slices whereas PLC was not effective. Thus, the severity of the perturbation of membrane integrity, and the inhibition of (Na(+) + K(+))-ATPase in brain membranes may play an important role in cellular swelling of brain slices induced by PLA(2).