Effect of noradrenaline on glycerol turnover and lipolysis in the whole body and subcutaneous adipose tissue in humans in vivo.

1. The effect of infusion of noradrenaline (0.42 mumol min-1 kg-1) on the exchange of nonesterified fatty acids, glycerol and other metabolites across subcutaneous abdominal adipose tissue was investigated in five healthy subjects using an arteriovenous catheterization technique and measurement of adipose tissue blood flow using the 133Xe clearance technique. At the same time, the net rate of fat oxidation in the whole body was assessed by indirect calorimetry, and the turnover of glycerol in the whole body and in subcutaneous adipose tissue was estimated using [5-2H]glycerol, which was administered as a primed constant infusion for 1 h before (basal turnover) noradrenaline administration and continued during the 1 h of noradrenaline infusion. 2. The noradrenaline infusion increased the plasma noradrenaline concentration from a basal value of 0.9 +/- 0.1 to 12.6 +/- 1.2 nmol/(mean +/- SEM) at 60 min. It also increased the arterialized concentration of glycerol by 50% (basal value 81 +/- 11 mumol/l-1) and that of plasma non-esterified fatty acids three-fold (basal value 357 +/- 86 mumol/l). 3. Noradrenaline increased the net release of glycerol by adipose tissue three-fold and that of non-esterified fatty acids three- to four-fold. Although the ratio of non-esterified fatty acid to glycerol release by adipose tissue increased in all subjects from a mean value of 2.7 in the basal period to 3.6 and 3.9 at 50 and 60 min of the noradrenaline infusion, respectively (P < 0.02), at no time point did the ratio differ significantly from 3.0.(ABSTRACT TRUNCATED AT 250 WORDS)