Abstract
The effect of neuromedin B (NMB) on insulin and glucagon release was studied in isolated perfused rat pancreases. Infusion of NMB (10nM, 100nM and 1μM) did not affect the insulin release under the perfusate conditions of 5.5mM glucose plus 10mM arginine and 11mM glucose plus 10mM arginine, although 10nM NMB tended to slightly suppress it under the perfusate condition of 5.5mM glucose alone. The degree of stimulation of insulin release provoked by the addition of 5.5mM glucose to the perfusate was not affected by the presence of 10nM NMB. The glucagon release was slightly stimulated by the infusion of 100nM and 1μM, NMB but not by 10nM NMB under the perfusate condition of 5.5mM glucose plus 10mM arginine. The effect of C-terminal decapeptide of gastrin releasing peptide (GRP-10) was also examined and similar results were obtained; 10nM and 100nM GRP-10 did not aifect insulin release and 100nM GRP-10 stimulated glucagon release under the perfusate condition of 5.5mM glucose plus 10mM arginine.
The present results concerning glucagon release are consistent with the previous results obtained with isolated perfused canine and porcine pancreas. However, the results regarding insulin release are not. Species differences in insulin release are also evident with other neuropeptides such as substance P and the mechanism of such differences remains fo be clarified.
