pH sensitivity of H+/organic cation antiport system in rat renal brush-border membranes

Journal Article · Mon Aug 15 04:00:00 EDT 1988 · J. Biol. Chem.; (United States)

OSTI ID:7070124

Maegawa, H; Kato, M; Inui, K; Hori, R

We examined the pH sensitivity of the H+/organic cation antiport system in brush-border membranes isolated from rat renal cortex. The uptake of tetraethylammonium, a typical organic cation, in the absence of an H+ gradient had a marked pH dependence with an optimum pH of 7.0, while the uptake of p-aminohippurate, an organic anion, and D-glucose was almost consistent in the pH range of 6.0-8.0. The decreased tetraethylammonium uptake by brush-border membrane vesicles, suspended in an acidic pH buffer or an alkaline pH buffer, was completely recovered by subsequent treatment of the vesicles with a pH 7.0 buffer. The pH sensitivity of tetraethylammonium uptake was not changed in the presence of either carbonyl cyanide p-trifluoromethoxyphenylhydrazone, a protonophore, or valinomycin (voltage-clamped condition). Kinetic parameters of tetraethylammonium uptake were changed in a pH-dependent manner, although Eadie-Hofstee plots of tetraethylammonium uptake were linear in the pH range of 6.0-8.0, indicating the existence of one mode of transport system at various pH values. At an acidic pH, the Km was increased without any change in Vmax value, compared with the values at pH 7.0. On the other hand, at an alkaline pH, the Vmax was decreased without a change in Km value. These results suggest that the H+/organic cation antiport system in renal brush-border membranes is very sensitive to pH (optimum pH of 7.0), in contrast to organic anion and D-glucose transport systems, and that pH is an important factor to regulate the activity of the H+/organic cation antiport system, as well as H+ gradient (a driving force).

• Research Organization: Kyoto Univ. (Japan)
• OSTI ID: 7070124
• Journal Information: J. Biol. Chem.; (United States), Journal Name: J. Biol. Chem.; (United States) Vol. 263:23; ISSN JBCHA
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALDEHYDES
AMMONIUM COMPOUNDS
ANIMALS
ANIONS
ANTI-INFECTIVE AGENTS
ANTIBIOTICS
BARYONS
BODY
CARBOHYDRATES
CATIONS
CELL CONSTITUENTS
CELL MEMBRANES
CHARGED PARTICLES
DRUGS
ELEMENTARY PARTICLES
FERMIONS
GLUCOSE
HADRONS
HEXOSES
IONS
KIDNEYS
MAMMALS
MEMBRANE TRANSPORT
MEMBRANES
MONOSACCHARIDES
NUCLEONS
ORGANIC COMPOUNDS
ORGANS
PH VALUE
PROTONS
RATS
RODENTS
SACCHARIDES
UPTAKE
VALINOMYCIN
VERTEBRATES