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The differential effects of circulating norepinephrine and neuronally released norepinephrine on sodium excretion in humans
Author(s) -
Lang Chim C,
Rahman Abdul R,
Balfour David J K,
Struthers Allan D
Publication year - 1993
Publication title -
clinical pharmacology and therapeutics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.941
H-Index - 188
eISSN - 1532-6535
pISSN - 0009-9236
DOI - 10.1038/clpt.1993.183
Subject(s) - norepinephrine , tyramine , endocrinology , medicine , natriuresis , phenylephrine , chemistry , renal sodium reabsorption , renal blood flow , effective renal plasma flow , reabsorption , blood pressure , kidney , dopamine
The renal effects of incremental infusions of norepinephrine (placebo, 0.025 µ/kg/min), 0.075 µ/kg/min, phenylephrine (placebo, 0.5 µg/kg/min, 2.5 µg/kg/min), and tyramine (placebo, 2 µg/kg/min, 15 µg/kg/min) were examined in three respective groups ( n = 9,8, and 8) of normotensive male subjects undergoing water diuresis. Tyramine is an indirect sympathetic agent that causes neuronal release of endogenous norepinephrine. Increases in mean arterial pressure during each high‐dose infusion were comparable in all three groups. Both norepinephrine and phenylephrine caused a decrease in urinary sodium excretion and effective renal plasma flow, with no changes in glomerular filtration rate. Proximal tubular sodium reabsorption, as assessed by both lithium clearance and solute‐free water clearance methods, was increased by pressor doses of norepinephrine and phenylephrine. In contrast, a similar pressor dose of tyramine was associated with a pressure natriuresis, an increase in effective renal plasma flow, and a decrease in proximal tubular sodium reabsorption. Our data indicate that, in normotensive humans, circulating catecholamines (norepinephrine and phenylephrine) have opposite effects on renal sodium handling from neuronally released norepinephrine (tyramine). Clinical Pharmacology and Therapeutics (1993) 54, 514–522; doi: 10.1038/clpt.1993.183