Effects of a beta-adrenergic receptor stimulant (isoproterenol) on pancreatic exocrine secretion

The effects of isoproterenol on pancreatic secretion was studied in five dogs with chronic pancreatic and gastric fistulas. Pancreatic secretion was stimulated by secretin or secretin with cholecystokinin-pancreozymin infusion; isoproterenol was administered during steady state secretion in doses of 0.25, 0.5, 1.0, and 2.0 μg per kilogram-minute. Marked inhibition of volume, HCO₃ concentration, and HCO₃ output occurred; the degree of inhibition was dose related (30 percent at 0.25 μg per kilogram-minute and 90 percent at 2.0 μg per kilogram-minute). Enzyme responses to secretin with cholecystokinin-pancreozymin were profoundly inhibited by all doses of isoproterenol equally. ED₅₀ for HCO₃ output was 0.6 μg per kilogram-minute but < 0.25 μg per kilogram-minute for enzyme output. These effects could be blocked by propanolol. Thus, isoproterenol, in doses which increase splanchnic blood flow, is an effective inhibitor of pancreatic electrolyte and enzyme secretion. This characteristic, coupled with its cardiovascular effects, suggests that it may be of potential value in the management of severe acute pancreatitis.