Calorigenic Effect of Norepinephrine Correlated with Plasma Free Fatty Acid Turnover and Oxidation*

Abstract

Human volunteers were given intravenous norepinephrine (0.13 to 0.31 [mu]g/kg/min.) for periods of 15 to 25 minutes. O2 consumption increased 21 [plus or minus] 8%, plasma free fatty acid (FFA) levels 127.[plus or minus]57%, and FFA turnover 74[plus or minus]53% over based values. Conversion of palmitate-1-C14 to C14O2, measured in 2 subjects, increased ap-proximately 200%. After prior intravenous administration of pro[long dash]nethalql [2-isopropylamino-l(2-naphthyl)ethanolhydrochloride], ablocker of adrenergic [beta]-receptors, the FFA-mobilizing effects of norepinephrine and its calorigenic action were markedly reduced or abolished. These results are compatible with the hypothesis previously presented (Eaton and Steinberg, J. Lipid Res. 2:376, 1961), that the calorigenic effect of the catecholamines is, to a major extent, directly related to their ability to mobilize body fat. It is further suggested that the hyper-metabolism of the hyperthyroid animal and the cold-adapted animal may similarly be related to accelerated FFA mobilization.