Transport of N1-methylnicotinamide across brush border membrane vesicles from rabbit kidney

Research output: Chapter in Book/Report/Conference proceedingChapter

6 Citations (Scopus)

Abstract

A preparation of isolated brush border membranes from the rabbit renal cortex was used to examine the characteristics of N1-methylnicotinamide (NMN) transport in the kidney. Transport was independent of the presence of Na+ under Na+ equilibrium conditions. However, outwardly directed Na+ gradients stimulated NMN uptake, whereas inwardly directed Na+ gradients inhibited NMN uptake. Transport appeared to involve two parallel processes: one saturable with a J(max) of 5 nmol·mg protein-1·min-1 and an apparent K(t) of 0.6 mM, and a second that behaved like passive diffusion. Countertransport of NMN was observed when vesicles were preloaded with either NMN or another organic cation, tetraethylammonium (TEA). TEA and several structural analogues, as well as a wide variety of other organic cations and bases, were effective inhibitors of NMN uptake, though nicotinamide and p-aminohippuric acid did not interact with the uptake process. Outwardly directed proton gradients (pH 6.0 in, 7.6 out) stimulated transport, suggesting that NMN uptake may involve a countertransport of H+. The electrical potential difference across the vesicle membrane was manipulated using gradients of the permeant organic ion thiocyanate (SCN-); an outwardly directed gradient of SCN- (i.e., a depolarizing condition) stimulated uptake and produced a transient accumulation of NMN above that noted at equilibrium, whereas an inwardly directed SCN- gradient inhibited uptake of NMN. The data can be explained by postulating the presence of an electrogenic NMN+-H+ antiporter in the rabbit luminal membrane that could play a role in organic cation secretion.

Original languageEnglish (US)
Title of host publicationAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Volume18
Edition6
StatePublished - 1985

Fingerprint

Microvilli
Cations
Tetraethylammonium
Rabbits
Kidney
Membranes
p-Aminohippuric Acid
Antiporters
Proton-Motive Force
Niacinamide
Protons
Proteins

ASJC Scopus subject areas

  • Medicine(all)

Cite this

Wright, S. (1985). Transport of N1-methylnicotinamide across brush border membrane vesicles from rabbit kidney. In American Journal of Physiology - Renal Fluid and Electrolyte Physiology (6 ed., Vol. 18)

Transport of N1-methylnicotinamide across brush border membrane vesicles from rabbit kidney. / Wright, Stephen.

American Journal of Physiology - Renal Fluid and Electrolyte Physiology. Vol. 18 6. ed. 1985.

Research output: Chapter in Book/Report/Conference proceedingChapter

Wright, S 1985, Transport of N1-methylnicotinamide across brush border membrane vesicles from rabbit kidney. in American Journal of Physiology - Renal Fluid and Electrolyte Physiology. 6 edn, vol. 18.
Wright S. Transport of N1-methylnicotinamide across brush border membrane vesicles from rabbit kidney. In American Journal of Physiology - Renal Fluid and Electrolyte Physiology. 6 ed. Vol. 18. 1985
Wright, Stephen. / Transport of N1-methylnicotinamide across brush border membrane vesicles from rabbit kidney. American Journal of Physiology - Renal Fluid and Electrolyte Physiology. Vol. 18 6. ed. 1985.
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