Diabetes, Vol 29, Issue 11 875-881, Copyright © 1980 by American Diabetes Association
Epinephrine-induced hypoaminoacidemia in normal and diabetic human subjects: effect of beta blockade
H Shamoon, R Jacob and RS Sherwin
To evaluate the effect of epinephrine on the circulating amino acids, we
infused epinephrine into normal human subjects and juvenile-onset diabetic
patients given a constant basal infusion of insulin. Epinephrine infusion
produced an identical 350--400 pg/ml rise in plasma epinephrine in both
groups. In normal subjects, epinephrine caused a progressive 26% reduction
in total circulating amino acids, despite unchanged levels of plasma
insulin. This effect was most pronounced for the branched amino acids,
which fell by 40% (P < 0.001). Plasma alanine was the only amino acid
which failed to decline. Similarly, infusion of epinephrine in the
insulin-infused diabetics produced a 23% fall in total amino acids, a 37%
decline in branched chain amino acids, but no change in plasma alanine.
Saline infusion in the insulin-infused diabetics had no effect on plasma
amino acid concentrations. In addition, when epinephrine was infused into
two insulin-withdrawn diabetics, a comparable hypoaminoacidemic response
was observed. The infusion of propranolol in both normal and diabetic
subjects totally prevented the epinephrine-induced fall in plasma amino
acids. It is concluded that (1) increments in epinephrine similar to those
observed in stress cause a decline in circulating amino acids (except
alanine) which is greatest for the branched chain amino acids; (2) this
hypoaminoacidemic effect occurs in the absence of a rise in plasma insulin
and diabetic subjects, as well; and (3) epinephrine-induced changes in
amino acid regulation are prevented by beta-adrenergic blockade. Our
findings suggest that, in contrast with glucose and fat metabolism,
epinephrine and insulin may have similar, rather than antagonistic, effects
on plasma amino acid metabolism.