Phospholipase a and lysophospholipase activities in isolated fat cells: Effect of cyclic 3'.5'-AMP

1. 1. Homogenates of fat cells, isolated from rat epididymal fat pads, were shown to contain phospholipase A and lysophospholipase activities. 2. 2. The highest phospholipase A activity was found at pH 8, but a separate optimum of lower activity was detected at about pH 5. 3. 3. By using I-[9,10-3H2]palmityl-2-[I-14C]Iinoleyl-glycero-3-phosphoryletha-nolamine it could be demonstrated that fatty acid ester linkages at both position 1 and 2 of the phosphatidylethanolamine were hydrolyzed at pH 8. 4. 4. Lipolysis at both positions of the phosphoglyceride was stimulated by cyclic 3',5'-AMP