The effect of endothelin-1, endothelin-2 and endothelin-3 in early cerulein-induced acute pancreatitis in rats.

PURPOSE To assess the effect of endothelins: ET-1, ET-2 and ET-3 on trypsinogen activation, lipase activity and histological changes in the pancreas in early (4 hrs) cerulein acute pancreatitis (AP) in rats. MATERIAL AND METHODS In 45 Wistar rats with cerulein induced AP (2 x 40 microg/kg i.p. at 1 hour interval, the effect of endothelins at the dose 2 x 0.5 or 2 x 1.0 nmol/kg i.p. was assessed vs untreated AP; 6 healthy rats were control (C). Free active trypsin (FAT), total potential trypsin after activation with enterokinase (TPT), lipase in 12000 xg supernatants of pancreatic homogenates and the plasma alpha-amylase were assayed. The %FAT/TPT was an index of trypsinogen activation. RESULTS %FAT/TPT increased from 3.0 +/- 0.6 in C to 16.2 +/- 3.1 in AP (p < 0.01). ET-1 decreased this index to 4.8 +/- 1.1 after higher dose (p < 0.01); the effect of lower dose was insignificant. Attenuating effect of ET-2 was significant: 7.3 +/- 1.7 after higher dose (p < 0.05) and 6.1 +/- 0.9 after lower dose (p < 0.01). ET-3 diminished this index to 4.5 +/- 1.5 (p < 0.01) and to 6.3 +/- 2.2 (p < 0.05) respectively. Lipase activity in supernatant increased from 4.1 +/- 0.6 in C to 6.3 +/- 0.7 U/mg protein in untreated AP (p < 0.05) and plasma alpha-amylase from 7.0 +/- 0.6 in C to 25.9 +/- 4.3 U/ml in AP (p < 0.001), without essential changes in treated groups vs untreated AP. Higher doses of endothelins decreased inflammatory cell infiltration score in AP. CONCLUSIONS The exogenous endothelins, especially ET-2 and ET-3 and to lesser extent ET-1 exerted some protective effect in early, edematous acute pancreatitis by the attenuation of trypsinogen activation and inflammatory cell infiltration in the pancreas.