Diabetes, Vol 24, Issue 6 247-251, Copyright © 1975 by American Diabetes Association
Calcium antagonists and islet function. I. Inhibition of insulin release by verapamil
G Devis, G Somers, E Van Obberghen and WJ Malaisse
Verapamil is a potent calcium antagonist known to inhibit
excitation-contraction coupling in both myocardium and myometrium. Its
effect upon glucose- and sulfonylurea-induced insulin release was
investigated in the isolated perfused rat pancreas. After twenty-five
minutes' pretreatment and at concentrations ranging between 0.8 and 8.1
muM, verapamil caused a dose-related inhibition of glucose-induced insulin
release during both the early and late phase of the secretory process. At a
concentration of 0.8 muM, the degree of inhibition was more marked when the
exposure time to verapamil prior to stimulation with glucose was increased
to sixty minutes. Verapamil also inhibited gliclazide-induced insulin
release. Infusion of verapamil during the late phase of the secretory
response to glucose demonstrated that the inhibition of insulin release was
an immediate and reversible phenomenon. The inhibitory effect of verapamil
was enhanced at a subnormal calcium concentration and reduced at a high
calcium concentration. These findings are consistent with the well-known
calcium dependency of both glucose- and sulfonylurea-induced insulin
release and suggest that verapamil might be a promising tool for further
studies on the interactions between cations and secretagogues in the
beta-cell secretory process.