Muscarinic inhibition of pancreatic B-cells.

Muscarinic agonists are known to potentiate insulin secretion and increase glucose-induced firing of pancreatic B-cells. Here we report two experimental situations in which inhibitory effects of muscarinic agonists may be observed. (1) Muscarinic agonists delay the onset of the 11.1 mM glucose-induced cell depolarization. (2) At concentrations between 10(-9) and 10(-7) M, acetyl-beta-methylcholine (and also bethanechol and MCN-a-343) decreases cell input resistance and decreases insulin release of islet cells exposed to 5.6 mM glucose.