In isolated rat islets the α2-adrenergic antagonist phenoxybenzamine was found to be only partially effective at relieving the inhibition of glucose-induced insulin secretion mediated by noradrenaline. Further experiment revealed a direct inhibitory effects of phenoxybenzamine itself on the secretory response to glucose. At concentrations above 1 μM the antagonist inhibited insulin secretion in a dose-dependent manner, with greater than 50% inhibition at 50 μM. The inhibition of secretion developed rapidly in perifused islets, and was not altered when islets were also incubated with idazoxan or benextramine, suggesting that it did not reflect binding of phenoxybenzamine to the α2-receptor. Paradoxically phenoxybenzamine significantly increased the basal secretion rate in the presence of 4 mM glucose. The results demonstrate that phenoxybenzamine can exert direct effects on insulin secretion which are unrelated to its α-antagonist properties.
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April 01 1989
Effects of phenoxybenzamine on insulin secretion from isolated rat islets of Langerhans
Susan L. F. Chan;
Susan L. F. Chan
1Department of Biological Sciences, University of Keele, Keele, Staffs ST5 5BG
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Noel G. Morgan
Noel G. Morgan
1Department of Biological Sciences, University of Keele, Keele, Staffs ST5 5BG
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Publisher: Portland Press Ltd
Received:
October 10 1988
Online ISSN: 1573-4935
Print ISSN: 0144-8463
© 1989 Plenum Publishing Corporation
1989
Biosci Rep (1989) 9 (2): 223–230.
Article history
Received:
October 10 1988
Citation
Susan L. F. Chan, Noel G. Morgan; Effects of phenoxybenzamine on insulin secretion from isolated rat islets of Langerhans. Biosci Rep 1 April 1989; 9 (2): 223–230. doi: https://doi.org/10.1007/BF01115999
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