AJP - Endocrinology and Metabolism, Vol 256, Issue 5 E619-E623, Copyright © 1989 by American Physiological Society
Effect of galanin on glucose-, arginine-, or potassium-stimulated insulin release
T. Yoshimura, J. Ishizuka, G. H. Greeley Jr and J. C. Thompson
Department of Surgery, University of Texas Medical Branch, Galveston 77550.
We have examined the effect of galanin infusion on glucose-stimulated
release of insulin from the isolated perfused pancreas of the rat to better
characterize the effect of galanin on the first and second phases of
insulin release. The effects of galanin on insulin release stimulated by
L-arginine or high concentrations of potassium were also examined. When
perfusion of galanin was started 4 min before the start of perfusion of
high glucose (16.7 mM), galanin (10(-8)-10(-11) M) inhibited both the first
and second phases of insulin release in a dose-dependent manner. When
perfusion of galanin (10(-8) or 10(-9) M) was started simultaneously with
high glucose (16.7 mM), only the second phase of insulin release was
suppressed (P less than 0.05). Galanin (10(-9) M) failed to inhibit insulin
release stimulated by L-arginine (10 and 5 mM) or potassium (25 and 20 mM).
These findings suggest that the inhibitory action of galanin on
glucose-stimulated insulin release is exerted on early intracellular events
that occur during the stimulation of insulin release and that are common to
both phases. Because galanin does not inhibit insulin release stimulated by
L-arginine or potassium, galanin may inhibit glucose-stimulated closure of
potassium channels.
