The integrity of rat pancreatic acinar cells under the influence of human phospholipase A2(PLA2) was studied. Isolated pancreatic acini showed no increased discharge of aspartylaminotransferase (ASAT) when incubated either in solutions containing human pancreatic PLA2or the bile salt sodium deoxycholate (DEC), the latter in concentrations that augment PLA2activity but have no destructive detergent effect. When human pancreatic PLA2was injected into the rat pancreatic duct, uneven distribution was observed at 15 min and 3 h in immunohistochemical sections. Edema and a mild inflammatory reaction were the main changes in the pancreas. The necrotic areas seen by light and electron microscopy were quite small and located mostly at the periphery of lobules corresponding the spread of the injected material. Necrosis was of the coagulation type and showed equal extent after the injection of PLA2with or without DEC. Internalized human pancreatic PLA2was present already 15 min after the injection in the cytoplasm of some intact acinar cells, indicating a functioning protective mechanism. It was concluded that pancreatic acinar cells are quite resistant to PLA2-catalyzed hydrolysis of membrane phospholipids in vitro, but additional trauma, e.g., pressure caused by intraductal injection, and tissue related factors, such as the mediators of the inflammatory reaction, make acinar cells susceptible to the effect of PLA2.
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