Functional roles of Na/sup +/ and H/sup +/ in SO/sup 2 -//sub 4/ transport by rabbit ileal brush border membrane vesicles

Journal Article · Sun Jan 01 00:00:00 EST 1984 · J. Membr. Biol.; (United States)

DOI:https://doi.org/10.1007/BF01925966· OSTI ID:6202273

Ahearn, G A; Murer, H

Sulfate uptake by rabbit ileal brush border membrane vesicles was stimulated by a transmembrane sodium gradient, but not by a similar potassium gradient. /sup 35/SO/sub 4/(/sup +2/) influx (JSO4 oi) from outside (o) to inside (i) these vesicles was a hyperbolic function of (SO/sub 4//sup +2/)o and the affinity constant for anion transport was strongly influenced by (Na/sup +/)o. JSO/sub 4/ oi was a sigmoidal function of (Na/sup +/)o at pH 7.4 for both low (0.2 M) and high (4.0 mM) (SO/sub 4//sup +2/)o. The Na/sup +/-dependency of JSO/sub 4/ oi was examined at pH 6.0, 7.4, and 8.0 (same pH inside and outside). When a H/sup +/ gradient was imposed across the vesicle wall (pHi . 8.0, pHo . 6.0), Na/sup +/-dependent JSO/sub 4/ oi was hyperbolic and significantly increased at each (Na/sup +/)o over values observed using bilateral pH 8.0. In contrast, a H/sup +/ gradient oriented in the opposite direction (pHi . 6.0, pHo . 8.0) led to Na/sup +/-dependent JSO/sub 4/ oi that was sigmoidal and significantly lower at each (Na/sup +/)o than values found using bilateral pH 6.0. Electrogenicity of JSO4 oi at pH 8.0 for both high and low (Na+)o was demonstrated by using a valinomycin-induced transmembrane electrical potential difference. A model is proposed for proton regulation of sodium sulphate cotransport where flux stoichiometry is controlled by (H/sup +/)i and sodium binding affinity is modified by (H/sup +/)o. Preliminary experiments with rabbit proximal tubular brush border membrane vesicles disclosed similar JSO/sub 4/ oi kinetic properties and a common transport mechanism may occur in both tissues.

• Research Organization: Univ. of Zurich, Switzerland
• OSTI ID: 6202273
• Journal Information: J. Membr. Biol.; (United States), Vol. 78:3
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
HYDROGEN COMPOUNDS
BIOLOGICAL EFFECTS
MEMBRANE TRANSPORT
KINETICS
STOICHIOMETRY
MUCOUS MEMBRANES
ELECTRIC POTENTIAL
SODIUM COMPOUNDS
SULFATES
SULFUR 35
TRACER TECHNIQUES
CATIONS
HILL EQUATION
INTESTINES
RABBITS
TUBULES
ALKALI METAL COMPOUNDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CHARGED PARTICLES
DAYS LIVING RADIOISOTOPES
DIFFERENTIAL EQUATIONS
DIGESTIVE SYSTEM
EQUATIONS
EVEN-ODD NUCLEI
GASTROINTESTINAL TRACT
IONS
ISOTOPE APPLICATIONS
ISOTOPES
KIDNEYS
LIGHT NUCLEI
MAMMALS
MEMBRANES
NUCLEI
ORGANS
OXYGEN COMPOUNDS
RADIOISOTOPES
SULFUR COMPOUNDS
SULFUR ISOTOPES
VERTEBRATES
551001* - Physiological Systems- Tracer Techniques