Studies of the cholinergic receptors involved in the secretion of insulin using isolated perfused rat pancreas.

Studies of the role and nature of the cholinergic receptors acting on the secretion of isolated perfused rat pancreas have shown the following: The infusion of acetylcholine at a dose of 2.5 μM in the presence of a concentration of glucose of 1.5 g/1, provoked a first phase of immediate and important stimulation of the secretion of insulin; this initial peak of insulin secretion was followed by a second phase during which a new less intense stimulation occurred; the latter was followed by an inhibition appearing at a time that depended on the pancreas used. At a dose of 0.5 μM of acetylcholine, the first phase of stimulation always appeared; during the second phase some pancreases were inhibited, others remained stimulated. - The peak of insulin secretion obtained by stimulation with acetylcholine during the first phase was dose related. - Eserine intensified the effects of acetylcholine. - The presence of glucose was essential for the insulinsecretory action of acetylcholine. The muscarinic nature of the cholinergic receptors implicated in the secretion of insulin was demonstrated by the use of: - Atropine which completely blocked the effects of acetylcholine, - Muscarine which produced the same effects as acetylcholine on our pancreas preparation, effects which were equally inhibited by atropine. The cholinergic receptors of the endocrine beta cell of the islet of Langerhans of the pancreas are therefore of the muscarinic type. [ABSTRACT FROM AUTHOR]