Effects of endothelin-1 or of its receptor A a selective antagonist, on histological and ultrastructural patterns in experimental acute pancreatitis in rats.

The role of endothelin-1 (ET-1) and of its receptor A (ETA) blockade in oedematous acute pancreatitis (AP) remains unclear. In 40 male Wistar rats with i.p. cerulein-induced AP, lasting 4 hours, ET-1 2x0.5 nmol/kg and 2x1.0 nmol/kg or selective ETA antagonist LU 302146, 10 mg/kg and 20 mg/kg was given i.p. simultaneously with cerulein. Histological and ultrastructural studies of pancreatic specimens were done. ET-1 decreased the inflammatory infiltration, but not the mean scores of necrosis and vacuolization in AP. The ultrastructural damage of acinar cells was less evident after ET-1 than in untreated AP. Selective ETA antagonist slightly aggravated the vacuolization and necrosis of acinar cells and some ultrastructural alterations in AP. In conclusion, ET-1, in contrast to selective ETA antagonist, exerts some protective effect in the early course of oedematous cerulein-induced acute pancreatitis in rats.