Comparative effect of somatostatin-14 and somatostatin-28 on glucagon-induced glycogenolysis from the perfused rat liver

Abstract The effect of somatostatin (SS)-14 and SS-28 on glycogenolysis was studied, using a rat liver perfusion technique. Livers from nonfasted rats were perfused with 5.5 mmol/L glucose or perfusate without the glucose addition. Glucagon-induced glucose output was lower in the presence of 5.5 mmol/L glucose than in glucose free perfusate at every concentration of glucagon. Under glucose free conditions, SS-14 given at five minutes prior to the glucagon addition reduced the glucagon-induced glucose output dose-dependently. SS-14 given 15 minutes after glucagon addition also inhibited glucagon-induced glucose output significantly. However, various concentrations of SS-28 failed to affect glucose output. On the other hand, in the presence of 5.5 mmol/L glucose, neither SS-14 nor SS-28 affected glucagon-induced glucose output. It is suggested, therefore, that glycogenolysis induced by glucagon from the liver is reduced by SS-14, but not by SS-28, only under glucose free conditions.