Contraindication for osmotic mini-pump in the abdominal cavity to study muscarinic cholinergic control of pancreatic enzyme secretion and muscarinic receptors.

Alzet mini-pumps were used to study modulation of rat pancreatic muscarinic receptors and the acinic secretory response to long-term N-methylscopolamine (NMS) treatment. Infused intraperitoneally (i.p.), NMS, 25 mg.kg-1.day-1 for 14 days, resulted in a shift to the left in the amylase dose-response curve to carbamylcholine (Cch) and an increase in receptor concentration compared to saline-infused group. Compared to previously published control data [4,5] the saline-infused group exhibited desensitization with increased EC50 for secretion. An alternative mode of saline treatment, subcutaneous (s.c.) infusion showed normal pancreatic secretory response. Desensitization by i.p. saline infusion was prevented by NMS infusion. In conclusion, a foreign body such as a mini-pump in the abdominal cavity can cause desensitization of the pancreatic secretory function under neural cholinergic control.