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Selective stimulation of glucagon secretion by β 2 ‐adrenoceptors in isolated islets of Langerhans of the rat
Author(s) -
Lacey Rosemary J.,
Berrow Nicholas S.,
Scarpello John H.B.,
Morgan Noel G.
Publication year - 1991
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1991.tb09870.x
Subject(s) - medicine , endocrinology , clenbuterol , glucagon , ibmx , stimulation , agonist , antagonist , chemistry , secretion , phosphodiesterase inhibitor , phosphodiesterase , biology , receptor , insulin , forskolin , enzyme , biochemistry
1 In rat isolated islets of Langerhans the selective β 2 ‐adrenoceptor agonist, clenbuterol (1 to 20 μ m ), significantly increased the level of adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) within 2 min of incubation. 2 The cyclic AMP response to clenbuterol was inhibited in the presence of the selective β 2 adrenoceptor antagonist, ICI 118551 (0.1 or 10 μ m ) but remained unchanged when the β 1 ‐antagonist, atenolol (0.1 μ m ) was administered. 3 Despite causing an elevation in cyclic AMP, clenbuterol (up to 20 μ m ) failed to influence insulin secretion at any glucose concentration tested, even in the presence of a phosphodiesterase inhibitor. 4 By contrast, clenbuterol elicited a dose‐dependent rise in the rate of glucagon secretion; the maximal agonist‐induced increase in secretion was two fold, a response equivalent to that observed with 20 m m l ‐arginine. 5 ICI 118551 significantly inhibited the rise in glucagon secretion induced by clenbuterol (up to 20 μ m ). 6 The results indicate that the rat islet A cell population is equipped with functional β 2 ‐adrenoceptors which influence glucagon secretion via the second messenger cyclic AMP, but that the B cells are deficient in functional β‐receptors.