Phospholipase A2 is a member of the class of heat-stable, calcium-dependent enzymes catalyzing the hydrolysis of the 2-acyl bond of 3-n-phosphoglycerides. The enzyme has a molecular weight of 30,000 daltons. Phospholipase A2 is activated by Ca2+. It is inhibited by zinc, barium, and manganese ions. Activity values for phospholipase A preparations which are derived from titrimetric assay procedures can be quite dependent on source and type of lecithin, its preparation as a substrate emulsion, other components of the reaction mixture, and the method and instrumentation used.Phospholipase A2 has been used in phospholipase assay and to determine rat renal proximal tubular segments (PTS) viability during oxygenation and hypoxia-reoxygenation.