Effect of Atropine on Rat Basal Pancreatic Secretion during Return or Diversion of Bile-Pancreatic Juice

The effect of atropine on basal pancreatic exocrine secretion in conscious rats was determined with and without return of bile–pancreatic juice (BPJ) to the intestine. Rats were prepared with cannulas draining bile and pancreatic juice separately and with duodenal cannulas for return of secretions. Experiments were begun 3 days postoperatively. During continuous return of bile-pancreatic secretions, intravenous atropine (100 μg/kg-hr) caused a sustained 80–90% inhibition of pancreatic protein secretion, with a much smaller suppressive effect on pancreatic juice volume. Diversion of bile-pancreatic juice from the intestine markedly increased pancreatic protein and fluid secretion in control and atropine-infused rats, but the response was significantly inhibited by atropine (volume 31% inhibition, protein output 41% inhibition). The results indicate that basal pancreatic protein secretion during return of BPJ is largely maintained by cholinergic influence, possibly due to an enteropancreatic reflex, and that the inhibition of the pancreatic response to acute diversion of BPJ by atropine is probably secondary to inhibition of gastric secretion.