Characterization of bicarbonate-dependent potassium uptake in cultured corneal endothelial cells

Journal Article · Sat Apr 01 04:00:00 EST 1989 · Invest. Ophthalmol. Visual Sci.; (United States)

OSTI ID:6155915

Savion, N; Farzame, N; Berlin, H B

Bovine corneal endothelial (BCE) cells in culture demonstrated 86Rb+ uptake which was mostly ouabain-sensitive with some (15 to 50%) ouabain-insensitive uptake that was dependent on the presence of bicarbonate in the incubation medium. Bovine smooth muscle (SM) cells demonstrated ouabain-sensitive 86Rb+ uptake but the ouabain-insensitive 86Rb+ uptake was not bicarbonate-dependent. Although omission of bicarbonate from the incubation buffer resulted in some reduction in the pH, this change was not responsible for the reduction in the ouabain-insensitive 86Rb+ uptake. Furthermore, the removal of bicarbonate decreased the 86Rb+ influx but not its efflux. This ouabain-insensitive and bicarbonate-dependent 86Rb+ influx in BCE cells proceeded at a linear rate for at least 60 min and increased as a function of bicarbonate concentration such that almost maximal uptake was observed at a concentration of about 10 to 15 mM. Saturation of the bicarbonate-dependent 86Rb+ pump in BCE cells occurred at a concentration of 2 mM Rb+ in the incubation buffer, similar to the previously observed value for the Na+, K+-ATPase. Competition experiments with both unlabeled Rb+ and K+ demonstrated that likewise in the Na+, K+-ATPase the 86Rb+ influx represented physiological influx of K+. Furthermore, the energy requirements of the bicarbonate-dependent 86Rb+ uptake were similar to those of the 86Rb+ uptake via the Na+, K+-ATPase. The results described in this work demonstrated a novel bicarbonate-dependent K+ pump in addition to the Na+, K+-ATPase pump.(ABSTRACT TRUNCATED AT 250 WORDS)

• Research Organization: Tel-Aviv Univ., Tel-Hashomer (Israel)
• OSTI ID: 6155915
• Journal Information: Invest. Ophthalmol. Visual Sci.; (United States), Journal Name: Invest. Ophthalmol. Visual Sci.; (United States) Vol. 30:4; ISSN IOVSD
• Country of Publication: United States
• Language: English

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550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ACID CARBONATES
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ANIMAL TISSUES
ANIMALS
ATP-ASE
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
BODY AREAS
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CATTLE
CELL CULTURES
CORNEA
DAYS LIVING RADIOISOTOPES
DOMESTIC ANIMALS
DRUGS
ENDOTHELIUM
ENZYMES
EYES
FACE
GLYCOSIDES
HEAD
HYDROLASES
INTERMEDIATE MASS NUCLEI
ISOMERIC TRANSITION ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
MAMMALS
MINUTES LIVING RADIOISOTOPES
MUSCLES
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANS
OUABAIN
PHOSPHOHYDROLASES
POTASSIUM COMPOUNDS
RADIOISOTOPES
RUBIDIUM 86
RUBIDIUM COMPOUNDS
RUBIDIUM ISOTOPES
RUMINANTS
SENSE ORGANS
STROPHANTHINS
TISSUES
TRACER TECHNIQUES
UPTAKE
VERTEBRATES