Norepinephrine: hormone and neurotransmitter in man.
To determine whether norepinephrine could subserve a hormonal as well as a neurotransmitter function, norepinephrine was infused for 60 min into each of five normal young men in doses of 0.1, 0.5, 1.0, 2.5, and 5.0 microgram/min. After infusion, the plasma norepinephrine concentration fell with a mean (+/-SD) half-time of 2.4 +/- 0.7 min. The mean (+/-SD) norepinephrine metabolic clearance rate was 3,070 +/- 200 ml/min. The calculated basal plasma norepinephrine production rate was 0.7 microgram/min. The blood pressure and circulating glycerol, acetoacetate, beta-hydroxybutyrate, and glucose (increased) and the heart rate and circulating insulin, lactate, pyruvate, and alanine (decreased) exhibited highly significant parabolic relationships with the steady-state plasma norepinephrine concentrations. However, norepinephrine levels in excess of 1,800 pg/ml were required to produce hemodynamic and/or metabolic effects. Thus, under usual conditions, the biologic actions of norepinephrine can be attributed only to its sympathetic neurotransmitter function. Plasma norepinephrine concentrations do at times exceed 1,800 pg/ml during exercise and during major acute illness. Thus, under conditions of stress, norepinephrine may subserve a hormonal, as well as a neurotransmitter, function.
D000328:Adult; D001786:Blood Glucose / Q000502:physiology; D001794:Blood Pressure / Q000187:drug effects; D005943:Gluconeogenesis; D006339:Heart Rate / Q000187:drug effects; D006728:Hormones / Q000502:physiology; D006801:Humans; D008297:Male; D008657:Metabolic Clearance Rate; D018377:Neurotransmitter Agents / Q000502:physiology*; D009638:Norepinephrine / Q000378:metabolism / Q000502:physiology*; D005082:Physical Exertion; D011187:Posture; D013569:Synapses / Q000378:metabolism; D014661:Vasoconstriction
D001786:Blood Glucose; D006728:Hormones; D018377:Neurotransmitter Agents; D009638:Norepinephrine