Effects of portal and peripheral venous insulin infusion on glucose production and utilization in depancreatized, conscious dogs.

The relation between portal vein insulin concentrations and suppression of hepatic glucose production, as well as peripheral venous insulin level and increase of peripheral glucose utilization, was compared in conscious, depancreatized, diabetic dogs after infusion of insulin at 0.25 and 0.5 mU/kg/min into either the portal system or the peripheral circulation. Glucose appearance and clearance was measured using [3-3H]-glucose. Before infusion of insulin, portal vein insulin concentrations were undetectable. The intraportal infusion of insulin at 0.25 mU/kg/min increased portal vein insulin to 16 +/- 1 microU/ml, significantly higher than the arterial concentration (9 +/- 1 microU/ml). Infusion of the same amount of insulin into a peripheral vein raised peripheral insulin levels to 14 +/- 1 microU/ml and portal vein concentrations to 12 +/- 1 microU/ml. When 0.5 mU/kg/min of insulin was infused into the portal system, the portal vein insulin level was 28 +/- 2 microU/ml and significantly greater than the arterial concentration (16 +/- 1 microU/ml). After the same amount of insulin was infused into a peripheral vein, the arterial insulin level was higher than that of the portal vein (25 +/- 1 microU/ml versus 20 +/- 1 microU/ml, respectively). The ensuing hypoglycemia was greater after the 0.5 mU/kg/min infusion compared with the 0.25 mU/kg/min infusion. At each dose there was no significant difference between the peripheral venous or the portal route.(ABSTRACT TRUNCATED AT 250 WORDS)