Epinephrine inhibits exogenous glucose utilization in exercising horses

Abstract

This study examined the effects of preexercise glucose administration, with and without epinephrine infusion, on carbohydrate metabolism in horses during exercise. Six horses completed 60 min of treadmill exercise at 55 ± 1% maximum O2 uptake 1) 1 h after oral administration of glucose (2 g/kg; G trial); 2) 1 h after oral glucose and with an intravenous infusion of epinephrine (0.2 μmol · kg-1 · min-1; GE trial) during exercise, and 3) 1 h after water only (F trial). Glucose administration (G and GE) caused hyperinsulinemia and hyperglycemia (~8 mM). In GE, plasma epinephrine concentrations were three- to fourfold higher than in the other trials. Compared with F, the glucose rate of appearan..