Action of phospholipase A2 of rabbit neuronal and glial cells on 1,2-diacyl-, 2-acyl-1-alk-1'-enyl-, and 2-acyl-1-alkyl-glycerophosphatides.

Pronounced differences in the phospholipase A2 activities were found in neurons and glia, the enzyme activity being two- to threefold higher in neurons than in glial cells. Both phospholipases A2 hydrolyzed the 1,2-diacylglycerophosphatides more rapidly than the acylalkyl and acylalkenyl compounds. Choline plasmalogen and the corresponding alkyl derivative were cleaved at similar rates by the phospholipase A2 from both glia and neurons. There was a tendency by the neuronal phospholipase A2 to release arachidonic acid faster than linolenic acid from both phosphatidylcholine and -ethanolamine, while arachidonic acid was removed less actively from phosphatidylethanolamine by the glial enzyme. The glial phospholipase A2 showed a lag period of 10 or 20 min. Norepinephrine, injection into the lateral ventricle of the rabbit brain, stimulated the hydrolysis of the various 1,2-diacyl-, acylalkyl, and and acylalkenyl-glycerophosphatides by the phospholipase A2 from both glia and neurons.