Abstract
We have used primed constant infusions of [1- 13C]palmitic acid, [2- 3H]glycerol, and [U- 14C]glucose to evaluate the response of glucose and fat kinetics to α or β adrenergic blockade in conscious dogs. The response of each blocking agent was evaluated both with and without control of the glucoregulatory hormones. When hormones were controlled, somatostatin and metyrapone were infused to block hormonal secretion, and insulin, glucagon, growth hormone, and cortisol were replaced at basal physiological rates. α blockade (β stimulation) did not influence glucose production or oxidation, but it did decrease glucose clearance when hormones were controlled. Clearance did not decrease during blockade when hormones were not controlled, presumably because of the resulting increase in the plasma insulin concentration. Glucose production, plasma glucose concentration, and glucose oxidation all increased with β blockade (α stimulation). α blockade (β stimulation) resulted in an increase in lipolysis, whereas β blockade (α stimulation) resulted in a decrease in lipolysis. In neither case, however, did FFA oxidation change. We conclude that (a) the predominant effect of unopposed stimulation is the stimulation of lipolysis, whereas unopposed α stimulation inhibits lipolysis. Direct effects of either α or β stimulation on glucose kinetics are less dramatic, but both α and β stimulation decrease glucose clearance.
Published Version
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