The effects of CoCl₂ on glucagon levels in plasma and pancreas of the rat

Fed, male adult rats were given an i.p. injection of CoCl₂ (25 mg./Kg.) after pretreatment with nicotinamide (750 mg./Kg.) to reduce the mortality rate. A trasient hyperglycemic phase was observed during the first hour after the injection and was accompanied by a significant increase in plasma glucagon levels, suggesting that the hyperglycemia may be due to a release of glucagon from the alpha cells. No evidence of significant depletion of pancreatic glucagon was observed during the 3 days after treatment nor did glucagon levels decline significantly at any time. It is suggested that, in the rat, CoCl₂ is more "alphacytotropic" than "alphacytotoxic" in its action and is ineffective in inducing even a temporary glucagon deficiency.