THE INVOLVEMENT OF MUSCARINIC RECEPTORS IN GASTRIC LIQUID EMPTYING INTHE CONSCIOUS RAT FOLLOWING ROUX-EN-Y-ANTRECTOMY

The gastric emptying of liquid test meals is dependent on resistance t o flow at the pylorus and on pressure gradients between the duodenum a nd the body of the stomach. In the present study, we investigated the role and subtypes of muscarinic receptors during gastric emptying of v arious liquid test meals in conscious rats with gastric fistula after Roux-en-Y antrectomy. In the control rats with gastric fistula but wit h intact reflex pathways and pylorus, the non-selective muscarinic ant agonist atropine (7 mg/kg i.p.) and Mi-selective pirenzepine (7 mg/kg i.p.), acting possibly on M1 receptors, delayed saline emptying by sup pressing cholinergic tone and thus relaxing the body of the stomach an d contracting the pyloric sphincter. On the other hand, in Roux-rats s aline and hyperosmolal saline emptying were not significantly affected , while the inhibitory effect of HCl was completely reversed. Furtherm ore, peptone-induced delay of gastric emptying in control rats was als o reduced in Roux-rats. Pirenzepine abolished the facilitating effects of Roux-en-Y operation on acid and peptone emptying and M2-selective antagonist AF DX-116 (7 mg/kg i.p.) did not have any inhibitory effect in this regard. In conclusion, Roux-en-Y gastrectomy without vagotomy does not slow gastric emptying of liquids, and it reverses the inhibi tory effects of peptone and acid through an atropine- and pirenzepine- sensitive pathway.