Inhibition of synaptosomal (Na+ + K+)-ATPase activity by lysophosphatidic acid: its possible role in membrane depolarization.
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 x 10(-6) M. 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.
Nishikawa
T
T
Department of Pharmacology, Kagoshima University Dental School, Japan.
Tomori
Y
Y
Yamashita
S
S
Shimizu
S
S
D000818:Animals; D002118:Calcium / Q000502:physiology; D004533:Egtazic Acid / Q000494:pharmacology; D066298:In Vitro Techniques; D008246:Lysophospholipids / Q000502:physiology*; D010712:Phosphatidic Acids / Q000502:physiology; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors*; D013574:Synaptosomes / Q000201:enzymology*
D008246:Lysophospholipids; D010712:Phosphatidic Acids; D004533:Egtazic Acid; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium