Lack of a direct alpha-adrenergic effect of epinephrine on glucose production in human subjects

Abstract

To determine whether alpha-adrenergic stimulation can directly increase glucose production in humans, we infused epinephrine plus propranolol in six normal subjects. The contribution of pancreatic islet effects was eliminated by the infusion of somatostatin. Despite high levels of epinephrine (1,234 +/- 255 pg/ml; mean +/- SE), plasma glucose fell from 85 + 1 to 71 +/- 7 mg/dl. Glucose production rate fell from 1.88 +/- 0.06 to 1.50 +/- 0.16 mg X kg-1 X min-1. During control studies in the same subjects (propranolol and somatostatin without epinephrine), plasma glucose fell from 87 +/- 1 to 75 +/- 3 mg/dl and glucose production fell from 1.93 +/- 0.10 to 1.58 +/- 0.13 mg X kg-1 X min-1. Thus, under conditions of suppressed insulin and falling glucose levels, both of which favor a positive response, a high level of alpha-adrenergic stimulation failed to directly increase glucose production. To ensure that the liver was not refractory to other stimuli, glucagon was administered during infusion of epinephrine and propranolol. In these studies, plasma glucose rose to 175 +/- 20 mg/dl and glucose production plateaued at 3.71 +/- 0.30 mg X kg-1 X min-1 (n = 7). These findings were similar to the effects of propranolol, somatostatin, and glucagon without epinephrine on plasma glucose (196 +/- 15 mg/dl) and glucose production (3.65 +/- 0.29 mg X kg-1 X min-1). Thus, although the liver remained responsive to glucagon during alpha-adrenergic stimulation, no alpha-adrenergic augmentation of glucose production was observed.(ABSTRACT TRUNCATED AT 250 WORDS)