The muscarinic receptor subtype in mouse pancreatic B-cells |
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Authors: | J C Henquin M Nenquin |
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Institution: | Unité de Diabétologie et Nutrition, University of Louvain, Faculty of Medicine, Brussels, Belgium. |
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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. |
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