The role of tubular secretion in the excretion of tritiated norepinephrine (3H-NE) released from renal symphathetic nerves was examined. The endogenous pool of NE in renal nerves in the superficial cortex of rabbits was labelled with 3H-NE by surface application of the isotope. Release of the 3H-NE was stimulated by surface application of tyramine (T). T significantly increased the urinary excretion of nonmetabolized 3H-NE. The increase was totally prevented by cyanine 863, but was not significantly affected by probenecid. Electrical stimulation of the renal nerves after intraarterial infusion of 3H-NE produced a 9 ± 3% increase (p< 0.025) in the excretion of nonmetabolized 3H-NE, but did not affect the excretion of 3H-metabolites. The data suggest that 3H-NE released from renal neurons can be excreted largely as nonmetabolized 3H-NE by cation-specific tubular secretion.
ASJC Scopus subject areas
- Biochemistry, Genetics and Molecular Biology(all)
- Pharmacology, Toxicology and Pharmaceutics(all)