ACTIVE PANCREATIC DIGESTIVE ENZYMES SHOW STRIKING DIFFERENCES IN THEIR POTENTIAL TO DAMAGE ISOLATED RAT PANCREATIC ACINAR-CELLS

Active digestive enzymes are involved in the pathophysiology of acute pancreatitis. Previous studies have mainly focused on the role of tryp sin in the autodigestive process. The present study compares the noxio us potential of different pancreatic enzymes to damage acinar cells. A cinar cells were isolated from rat pancreas by collagenase digestion. Cell viability was studied by (1) exclusion of trypan blue, (2) releas e of lactate dehydrogenase, and (3) release of newly synthesized prote ins identified with methionine labeled with sulfur 35. Cells were then incubated in oxygenated N-2-hydroxyethylpiperazine-N-'-2-ethanesulfon ic acid-Ringer solution containing different concentrations of various active digestive enzymes. Uptake of trypan blue was the most sensitiv e and reliable test of cell damage when compared with release of lacta te dehydrogenase or radiolabeled newly synthesized proteins. All activ e digestive enzymes studied caused dose-dependent cell damage. The nox ious potential, however, was strikingly different for the various enzy mes. Pancreatic elastase in nanomolar concentrations caused marked cel l damage otter 45 to 90 minutes of incubation. Lipase and chymotrypsin caused a similar damage only at micromolar concentrations, whereas ev en millimolar concentrations of trypsin failed to cause significant da mage. The present results confirmed recent work showing that lipase an d phospholipase A(2) probably cause cell damage through release of fre e fatty acids and lysolecithin. Although activation of trypsin might b e the trigger to start the activation cascade in acute pancreatitis, t rypsin itself is markedly less noxious to acinar cells when compared w ith other digestive enzymes. Elastase by far had the greatest noxious potential of all enzymes evaluated. Studies analyzing therapeutic effe cts of protease inhibitors should evaluate not only the inhibitory pot ential against trypsin but also that against other digestive enzymes, particularly elastase.