Six normal humans each underwent infusions of 1) saline; 2) propranolol; 3) somatostatin; 4) somatostatin with propranolol; and 5) somatostatin with propranolol plus phentolamine on separate occasions. Propranolol alone had no effect on glucose production or plasma glucose. Somatostatin alone produced the expected initial decrease followed by an increase in both hepatic glucose production and plasma glucose. β-Adrenergic blockade with propranolol displaced the glucose production (MANOVA, P = 0.0220) and plasma glucose (MANOVA, P = 0.0057) somatostatin response curves to higher levels, whereas α-adrenergic blockade with phentolamine combined with β-adrenergic blockade displaced the glucose production (MANOVA, P = 0.0281) and plasma glucose (MANOVA, P = 0.0134) somatostatin response curves to lower levels. Because plasma insulin, C-peptide, and glucagon were suppressed comparably under all three conditions and plasma glucose concentrations were comparable initially, this represents direct α-adrenergic stimulation of hepatic glucose production in postabsorptive humans demonstrable when the primary glucoregulatory hormones are withdrawn and β-adrenergic mechanisms are blocked. It is best attributed to sympathetic neural norepinephrine release.
|Journal||American Journal of Physiology - Endocrinology and Metabolism|
|State||Published - 1983|