The mechanism of glucose-induced catecholamine stimulation

Catecholamines are important hormones for maintaining homeostasis and may be secreted in response to several different stimuli. A report by Robertson and Porte in 1974 made the unexpected observation that acute administration of hypertonic glucose stimulates catecholamine secretion. Our study reassessed this observation by measuring individual catecholamines, explored its potential mechanism, and quantitated it relative to exercise and hypoglycemia-stimulated catecholamine secretion. We hypothesized that the mechanism of glucose-induced catecholamine secretion was related to an acute increase in plasma osmolality, which we tested with the nonmetabolizable hexose mannitol. In 56 studies, 14 normal adults underwent 4 partially randomized studies. The 4 study conditions consisted of the following: (1) rapid intravenous injection of 20 g of glucose; (2) rapid intravenous injection of 20 g of mannitol; (3) acute exercise (80 J/kg); and (4) insulin-induced hypoglycemia. Our results demonstrate that a significant increase in plasma catecholamine concentration occurs following each of the above stimuli, but its composition differs relative to the magnitude of epinephrine versus norepinephrine secretion. We conclude that the mechanism of glucose-induced catecholamine stimulation is the acute elevation in plasma osmolality induced by glucose, and that its stimulation is less than that which occurs following exercise for norepinephrine and less than that which occurs following hypoglycemia for epinephrine.