Abstract
Lysophosphatidic acid (LPA), a metabolite of phosphatidic acid (PA) by phospholipases of the A2 type, markedly inhibited the synaptic membrane (Na++K+)-ATPase activity from rat cerebral cortices in incubation media containing free Ca2+ concentrations below 4.7×10-6M. This effect of LPA was dose-dependent, and the minimum effective concentration was 10-6 g/ml. The inhibitory action of LPA was more potent than that of PA. Lysophosphatidylinositol (LPI) and lysophosphatidylethanolamine (LPE) at 10-5 g/ml had little or no effect on this enzyme activity. These results suggest that LPA may partly play a role in the depolarization and/or increase in intracellular calcium concentrations in the brain.
