Cyclic-AMP and Pancreatic Bicarbonate Secretion in Response to Secretin in Dogs

Abstract

In anesthetized dogs given secretin i.v. in doses doubling every 60 min and ranging from 0.5-8 units/kg body weight per h, cyclic-AMP levels in pancreatic tissue rose continuously, whereas DNA concentrations were slightly decreased. Bicarbonate concentrations and bicarbonate outputs, cyclic-AMP tissue concentrations and bicarbonate outputs, as well as cyclic-AMP tissue concentrations and juice outputs, were significantly correlated. In conscious pancreatic fistula dogs, there was a significant correlation between cyclic-AMP and bicarbonate concentrations and outputs in the pancreatic juice after stimulation by exogenous secretin. Enhanced release of endogenous secretin achieved by intraduodenal acidification led to a dose-dependent increase in bicarbonate and cyclic-AMP outputs in both conscious and anesthetized dogs. Phosphodiesterase inhibitors (aminophylline, caffeine, and papaverine) given alone to the conscious dogs did not initiate pancreatic bicarbonate secretion, but they potentiated bicarbonate responses to exogenous secretin. Cyclic-AMP may play a part in secretin-stimulated pancreatic secretion.