Opposing Actions of Glucagon and Insulin on Splanchnic D Cell Function

The effect of glucagon at various infusion rates on plasma levels of somatostatin-like immunoreactivity (SLI) was examined in conscious normal and chronic alloxan diabetic dogs. In normal dogs glucagon infused at 6, 36, and 120 ng/kg per min did not affect the peripheral venous plasma SLI levels. In diabetic dogs, however, peripheral venous plasma SLI levels in inferior vena cava rose significantly from a mean base-line value of 181±9 pg/ml to a peak value of 279±38 pg/ml during the infusion of 120 μg/kg per min of glucagon, which raised plasma immunoreactive glucagon to >5,000 pg/ml. This glucagon-mediated increase was completely abolished by coinfusion of 7 mU/kg per min of insulin, a rate that maintained the ratio of insulin to glucagon at approximately the baseline value.