COMPARTMENTAL MODELING OF GLUCAGON KINETICS IN THE CONSCIOUS DOG

The aim of the present study was to examine glucagon metabolism and distribution using both compartmental-modeling approaches and steady-state organ-balance techniques in conscious, overnight-fasted dogs. Arterial plasma glucose concentrations were clamped at 14 mmol/L with a variable exogenous glucose inf usion. Somatostatin was inf used to block endogenous secretion of insulin and glucagon. Insulin was replaced intraportally at 2.4 pmol . kg(-1) . min(-1) to maintain basal insulin concentrations in the range from 70 +/- 4 to 95 +/- 12 pmol/L. Glucagon was not given during the control period, but was subsequently infused peripherally in four 1-hour steps of 1.0, 3.0, 6.0, and 3.0 ng . kg(-1) . min(-1). Glucagon levels increased from 0 to 68 +/- 6, 195 +/- 19, 378 +/- 47, and 181 +/- 20 ng/mL. Compartmental analysis of glucagon concentrations showed that glucagon was distributed in one compartment with a volume approximately equal to the plasma volume. The metabolic clearance rate of glucagon was 17.6 mL . kg(-1) . min(-1). The liver cleared 24% of glucagon, and the kidneys, 17%. Copyright (C) 1995 by W.B. Saunders Company