Effects of physiological infusion of epinephrine in normal humans: Relationship between the metabolic response and β-adrenergic binding

In normal humans, infusion of epinephrine for 4 h increased plasma epinephrine to 411 ± 38 pg/ml but had no significant effect on plasma insulin or glucagon levels. Epinephrine produced a prompt 45% rise in glucose output (P < 0.01) and a 120% rise in FFA (P < 0.001), both of which declined to basal levels by 60-90 min. Glucose clearance decreased by 25% (P < 0.005) and remained suppressed for 4 h. The binding of [¹²⁵I]hydroxybenzylpindolol to lymphocytes was unchanged after epinephrine infusion. We conclude that in normal humans 1) physiological increments in epinephrine have' a persistent effect in decreasing glucose clearance but only transiently increase hepatic glucose output and FFA levels and 2) this refractoriness of liver and adipose tissue to epinephrine occurs without a concomitant decrease in β-adrenergic binding to lymphocytes.