Transport of urate and p-aminohippurate in rabbit renal brush-border membranes.
The mechanisms involved in urate and p-aminohippurate (PAH) transport in the rabbit renal brush-border membrane were investigated through study of membrane vesicles. Transport of [14C]urate and [3H]PAH was measured by a rapid filtration method. As previously reported by others, no OH(-)-PAH exchanger could be demonstrated by imposing an outwardly directed OH- gradient (pHin 7.4, pHout 6). In contrast, an OH(-)-lactate exchanger (or H(+)-lactate cotransport) was demonstrated. In the presence of valinomycin and an inwardly directed K+ gradient, both [14C]urate and [3H]PAH vesicle uptake were stimulated, demonstrating a potential-driven transport of these two anions. Probenecid, PAH, or cold urate decreased potential-driven urate uptake, suggesting that this transport was facilitated by a specific transport mechanism. The potential-driven urate transport described here may play a role in the second step of urate secretion in rabbits, because rate (or PAH) is transported across the brush-border membrane from the negative interior of the cell to the more positive omen.
Martinez
F
F
Institut de Pharmacologie de l'Université, Lausanne, Switzerland.
Manganel
M
M
Montrose-Rafizadeh
C
C
Werner
D
D
Roch-Ramel
F
F
D000618:Aminohippuric Acids / Q000378:metabolism*; D000818:Animals; D000838:Anions / Q000378:metabolism; D001692:Biological Transport; D002352:Carrier Proteins / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D007474:Ion Exchange; D007668:Kidney / Q000378:metabolism* / Q000648:ultrastructure; D007773:Lactates / Q000378:metabolism; D019344:Lactic Acid; D008564:Membrane Potentials; D008871:Microvilli / Q000378:metabolism / Q000502:physiology; D011817:Rabbits; D013696:Temperature; D014527:Uric Acid / Q000378:metabolism*; D010130:p-Aminohippuric Acid / Q000378:metabolism*
D000618:Aminohippuric Acids; D000838:Anions; D002352:Carrier Proteins; D007773:Lactates; D014527:Uric Acid; D019344:Lactic Acid; D010130:p-Aminohippuric Acid