Abstract
Quinine at low concentrations (0.05-0.1 mM) facilitated glucose-stimulated 45Ca net uptake and insulin release in isolated rat pancreatic islets. At higher concentrations (0.25-0.5 mM), quinine inhibited both 45Ca net uptake and insulin release. Quinine caused a dose-related inhibition of the translocation of Ca from an aqueous medium into an organic immiscible phase, as evoked by either the antibiotic ionophore X537A or an islet extract. Quinine also inhibited the process of X537A-mediated Na-Ca countertransport. It is proposed that the inhibitory effect of quinine, at high concentrations, upon insulin release may be due to a direct interference with the transport of Ca across the membrane system(s) in the islet cells.
ACKNOWLEDGMENTS The authors are grateful to M, Mahy, S. Procureur, J. Schoonheydt, and M. Urbain for technical assistance and C. Demesmaeker for secretarial help.
- Copyright © 1980 by The American Society for Pharmacology and Experimental Therapeutics
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