Effects of nicardipine on pancreatic exocrine secretion in the dog

Effects of synthesized phosphodiesterase inhibitors, DM 9278 and HWA 285, on pancreatic exocrine secretion of the dog

The effects of synthesized phosphodiesterase inhibitors, DM 9278 and HWA 285, on pancreatic exocrine secretion were investigated in isolated and blood-perfused canine pancreas. Close-arterial injections of DM 9278 (10-300 micrograms) and HWA 285 (300-3000 micrograms) caused dose-dependent increases in the flow rate of pancreatic juice and perfusion blood flow. Bicarbonate concentration in the pancreatic juice stimulated by DM 9278 (300 micrograms) or HWA 285 (3000 micrograms) was significantly higher than that in the resting pancreatic juice, although neither of the compounds affected protein concentrations in the pancreatic juice. In the secretory volume, 100 micrograms of DM 9278 corresponded roughly to 1000 micrograms of HWA 285, 0.1 units of secretin or 0.3 units of pancreozymin. These secretory and vascular effects were not modified by pretreatment with atropine or sulpiride. This study suggests that both DM 9278 and HWA 285 act directly on ductular cells of the pancreas and induce secretion of water and electrolytes.

Secretory and vascular effects of the optical isomers of nicardipine

The effects of optical isomers of nicardipine on the secretion of pancreatic juice and blood flow were investigated in the dog-isolated, blood-perfused pancreas. Intra-arterial administration of (-)-nicardipine (10-300 micrograms) caused a dose-dependent increase in pancreatic secretion. However, the (+)-isomer was much less potent than the (-)-isomer and even in 300 micrograms of (+)-isomer caused only a slight secretion. (+)- And (-)-nicardipine increased perfusion blood flow in a dose-dependent manner, and (+)-nicardipine was approximately five times as potent as the (-)-isomers. The maximum increase in a flow rate was produced by 30 micrograms of (+)-isomer and 100 micrograms of (-)-isomer. Bicarbonate concentration in pancreatic juice induced by (-)- and (+)-nicardipine was increased in a dose-dependent manner, but the protein concentration was only increased slightly. From these results, it is concluded that there is a stereoselectivity in the secretory and vascular actions of optical isomers of nicardipine.