Inhibition of Insulin Release Induced by Galanin in the Dog Is Not Exclusively Mediated by Activation of ATP-Sensitive K+ Channels

Exogenous galanin (9 pmol/min during 20 min i.a.) decreased insulin levels in the plasma sampled from the pancreatic vein of the blood-perfused pancreas of dogs in which ganglionic transmission and beta-adrenoceptors had been blocked. This effect was not modified by idazoxan (1 mg/kg followed by 0.02 mg/kg/min i.v.) but was partially reduced (50%) by glibenclamide (1 mg/kg followed by 0.02 mg/kg/min i.v.). This dose of glibenclamide blocked entirely the hypoinsulinemic activity of diazoxide, an activator of pancreatic ATP-modulated K+ channels, whereas the dose of idazoxan prevented the effect of the alpha 2-adrenoceptor agonist UK-14,304. Therefore, in dogs, the decrease in insulin secretion produced by exogenous galanin is only partially mediated by activation of glibenclamide-sensitive ATP-gated K+ channels and is independent of alpha 2-adrenoceptor stimulation.