title: The muscarinic receptor subtype in mouse pancreatic B-cells.
abstract: Isolated mouse islets were used to identify the muscarinic receptor subtype present in pancreatic B-cells. We thus compared the inhibitory potencies of atropine (non-specific), of pirenzepine (specific for M1 receptors) and of compound AF-DX 116 (specific for cardiac M2 receptors) on acetylcholine-induced insulin release, 86Rb+ efflux and 45Ca2+ efflux. The three antagonists inhibited all effects of acetylcholine, but EC50 values were markedly different: atropine = 1.5-5 nM, pirenzepine = 0.6-1.7 microM and AF-DX 116 = 1.7-11 microM. The results did not suggest that the various effects of ACh could result from the activation of different subtypes of receptors. It is concluded that muscarinic receptors of pancreatic B-cells belong to an M2 subtype distinct from the cardiac M2 receptors.
mesh_terms: D000109:Acetylcholine / Q000378:metabolism; D000818:Animals; D001285:Atropine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D005260:Female; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000187:drug effects / Q000378:metabolism*; D051379:Mice; D010890:Pirenzepine / Q000031:analogs & derivatives* / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000032:analysis* / Q000187:drug effects; D012414:Rubidium Radioisotopes
chemical_list: D007328:Insulin; D011976:Receptors, Muscarinic; D012414:Rubidium Radioisotopes; D010890:Pirenzepine; D001285:Atropine; D000109:Acetylcholine; C048593:otenzepad; D011188:Potassium; D002118:Calcium