MPP+ is transported by the TEA+-H+ exchanger of renal brush-border membrane vesicles

K. D. Ayer Lazaruk, S. H. Wright

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36 Scopus citations


Rabbit renal brush-border membrane vesicles (BBMV) were used to study the transport of the cationic neurotoxin, 1-methyl-4-phenylpyridinium (MPP+). An outwardly directed H+-gradient stimulated MPP+ uptake and led to the development of an active accumulation of MPP+ within the vesicles. H+-gradient driven MPP+ transport was saturable, with a maximal transport rate of 3 nmol · mg-1 · min-1 and an apparent Michaelis constant (K(t)) of 8 μM. MPP+ and tetraethylammonium (TEA) behaved as competitive inhibitors of one another's transport in renal BBMV, suggesting the presence of a common transport pathway for these organic cations. At an ambient pH of 7.5, preloading BBMV with MPP+ failed to stimulate TEA uptake, although trans TEA did stimulate MPP+ uptake. Increasing ambient pH to 8.5 (i.e., reducing competition between H+ and these organic cations for a common transport pathway) led to a clear reciprocal trans stimulation of TEA and MPP+ fluxes. With an equilibrium-shift protocol, a trans concentration of MPP+ energized uphill transport of TEA. We conclude that MPP+ and TEA share a common organic cation-H+ exchange pathway in the renal brush border, although turnover of an MPP+-loaded exchanger is slow compared with that for a TEA or H+-loaded exchanger.

Original languageEnglish (US)
Pages (from-to)F597-F605
JournalAmerican Journal of Physiology - Renal Fluid and Electrolyte Physiology
Issue number3 27-3
StatePublished - 1990


  • 1-me thyl-4-phenyl-1,2,3,6-tetrahydropyridine
  • 1-methyl-4-phenylpyridinium
  • countertransport
  • kidney
  • organic cation
  • rabbit
  • tetraethylammonium

ASJC Scopus subject areas

  • Physiology


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