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Horm Metab Res 1988; 20(3): 150-153
DOI: 10.1055/s-2007-1010780
ORIGINALS
Basic
© Georg Thieme Verlag, Stuttgart · New York

Evidence That Muscarinic Receptors in Islet Cells are Not Coupled Functionally to Adenylate Cyclase Through the Inhibitory Guanine Nucleotide Binding Protein (Ni)

Marjorie Dunlop, Margaret Shaw, Eva Dimitriadis, V. Gurtler, J. Wark, R. G. Larkins
  • University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Victoria, Australia
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Publication History

1987

1987

Publication Date:
14 March 2008 (online)

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Summary

The effect of muscarinic agonist on adenylate cyclase was investigated in neonatal islet cells and in a clonal pituitary cell line (GH4C1) following labelling of the intracellular ATP pool with [2, 83H]adenine. In islet cells carbamylcholine was without effect on basal or glucagon-stimulated adenylate cyclase activity, measured as 3H cyclic AMP production, but inhibited 3H cyclic AMP production in the clonal pituitary cells. The involvement of the inhibitory guanine nucleotide binding protein of adenylate cyclase (Ni) was investigated by the use of the Bordetella pertussis exotoxin, islet activating protein (IAP). Pre-treatment of islet cells with IAP was without effect on adenylate cyclase following carbamylcholine but in the clonal pituitary line abolished the inhibition of 3H cyclic AMP production. It is concluded that in the islet cell, in contrast to the clonal pituitary cell, muscarinic receptors are not effectively coupled through Ni to inhibit adenylate cyclase.

Key-Words

Adenylate Cyclase - Muscarinic Receptor - Pertussis Toxin - Pancreatic Islet - Clonal Pituitary Cell

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