Na sup + and H sup + transport in human jejunal brush-border membrane vesicles

Journal Article · Mon Aug 01 00:00:00 EDT 1988 · American Journal of Physiology; (USA)

OSTI ID:6940673

Kleinman, J G; Harig, J M; Barry, J A; Ramaswamy, K ^[1]

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1. Medical College of Wisconsin, Milwaukee (USA)

The authors have examined pH gradient-driven Na{sup +} uptake and Na{sup +}-driven H{sup +} transport in brush-border membrane vesicles prepared from jejunal tissue obtained from organ donors by measuring the influx of {sup 22}Na and the fluorescence quenching of acridine orange (AO). Vesicle preparation by either Ca{sup 2+} or Mg{sup 2+} precipitation showed no difference in {sup 22}Na uptake or AO fluorescence quenching and dissipation. An outward H{sup +} gradient induced a Na{sup +} uptake overshoot of threefold over equilibrium, whereas the absence of an H{sup +} gradient did not produce an overshoot. The initial rate of pH-driven Na{sup +} uptake in voltage-clamped vesicles was related to (Na{sup +}{sub o}). Amiloride inhibited this uptake in voltage-clamped vesicles. Dissipation of AO fluorescence quench in vesicles with a preformed internal acid gradient was hastened by Na{sup +}{sub o} as well as voltage clamping in the absence of Na{sup +}. In vesicles without a pH gradient, internal Na{sup +}, as well as a diffusion potential in the absence of Na{sup +}, induced AO quenching. External Na{sup +} and Li{sup +}, but not choline, acted to dissipate AO quenching induced by a diffusion potential, and the rate of dissipation was unaffected by the presence of Cl{sup {minus}}. Li{sup +} and NH{sup +}{sub 4}, but not Cs{sup +}, K{sup +}, Rb{sup +}, or choline{sup +}, inhibited pH gradient-driven {sup 22}Na uptake. They conclude that human jejunal brush-border membrane vesicles contain conductive pathways for both Na{sup +} and H{sup +} and an Na{sup +}-H{sup +} exchanger.

• OSTI ID: 6940673
• Journal Information: American Journal of Physiology; (USA), Vol. 255:2; ISSN 0002-9513
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
IONS
UPTAKE
MEMBRANE TRANSPORT
BIOCHEMICAL REACTION KINETICS
SODIUM 22
ACRIDINES
ANTIBIOTICS
CATIONS
DOSE-RESPONSE RELATIONSHIPS
PH VALUE
PROTONS
SMALL INTESTINE
ALKALI METAL ISOTOPES
ANTI-INFECTIVE AGENTS
AROMATICS
AZAARENES
AZINES
BARYONS
BETA DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BODY
CHARGED PARTICLES
DIGESTIVE SYSTEM
DRUGS
ELEMENTARY PARTICLES
FERMIONS
GASTROINTESTINAL TRACT
HADRONS
HETEROCYCLIC COMPOUNDS
INTESTINES
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KINETICS
LIGHT NUCLEI
NUCLEI
NUCLEONS
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PYRIDINES
RADIOISOTOPES
REACTION KINETICS
SODIUM ISOTOPES
YEARS LIVING RADIOISOTOPES
550201* - Biochemistry- Tracer Techniques