Metabolic responses to repeated infusions of identical doses of norepinephrine in chronically energy deficient human subjects.

ABSTRACT

The physiological effects of three 30 min infusions of identical doses of norepinephrine (0.15 microgram/kg FFM/min) separated by 60 min intervals were assessed in well nourished (WN; n = 6) and chronically energy deficient (CED; n = 6) subjects. Each subject also underwent control, vehicle infusions with 0.9 per cent saline on a separate day. Oxygen consumption (VO2) was significantly higher during the third infusion of NE as compared to the first in both groups. This increment in VO2 occurred despite similar plasma peak NE levels in both infusions. Increments in plasma glucose and free fatty acids were also similar during the first and third infusions. The study demonstrates that thermogenic potentiation which we had earlier demonstrated in WN subjects, occurs in CED subjects as well. Thermogenic potentiation is not associated with altered plasma NE kinetics or mobilisation of substrates.