Effect of atropine on different phases of pancreatic secretion in conscious rats

The effect of submaximal doses of intravenous atropine and their combination with topical anaesthesia of the intestine by oxethazaine-HCl was investigated in conscious rats. I. Basal water, bicarbonate and protein secretion were significantly augmented after diversion of pancreatic juice. On the basis of the protein secretory pattern of basal secretion, 2 stable stages have been recognized: 1. The most physiological basal stage during return of pancreatic juice. 2. The first, highly elevated plateau from the 4th to the 7th 30 min period after diversion. 3. The second delayed and less elevated plateau after 240 min diversion. II. Atropine greatly suppressed protein secretion during recirculation but only moderately after diversion of juice, and during the first plateau an atropine resistant peak appeared. Inhibition of water secretion was equal during all the stages. Atropine infusion resulted in a further decrease in pancreatic secretion also after topical anaesthesia of the intestine. It was concluded that atropine had a complex effect on pancreatic secretion: it possibly decreased the CCK release in the first period after diversion but not later, and decreased the duodenopancreatic reflexes and other factors of the cholinergic tone.