Na/sup +//Ca/sup 2 +/ exchange system of the liver cell

Journal Article · Tue Jan 01 04:00:00 EST 1985 · Res. Commun. Chem. Pathol. Pharmacol.; (United States)

OSTI ID:5411155

Bernstein, J; Santacana, G

The efflux of /sup 45/Ca (Ca/sub eff/) from rat liver slices incubated in a Krebs Ringer bicarbonate buffer showed two components with first order rate constants (kCa) of 0.0625 min-1 and 0.0101 min-1 respectively. The slow component corresponds to Ca/sub eff/ from the intracellular medium. Ouabain decreased kCa from the slow component (ksCa) by about 30%. External Na/sup +/ or Ca/sup 2 +/ did not affect ksCa. However, the inhibitory effect of ouabain was not observed in the absence of either Na/sup +/ or Ca/sup 2 +/ from the incubation medium. Concomitant to a decrease in ksCa, ouabain increased /sup 45/Ca uptake (Ca/sub up/) by about 30%. Sodium ionophores also increased Ca/sub up/, an effect which was not observed in the absence of external Na/sup +/. /sup 22/Na efflux was inhibited 50% by ouabain. In the presence of ouabain, external Ca/sup 2 +/ was able to significantly increase ksNa from 0. 0475 min-1 to 0.0506 min-1. External Na/sup +/ did not affect ksCa from preloaded slices containing high calcium and low sodium when incubated in a Ca/sup 2 +/-free medium. These results would indicate that a Na/sup +//Ca/sup 2 +/ exchange system in operative in the plasma membrane of the hepatocyte. It is estimated that about 60% of the calcium entering the hepatocyte moves in through this exchanger. The evidence obtained also suggests that the Na/sup +//Ca/sup 2 +/ exchanger operates unidirectionally, extruding internal Na+ in exchange for external Ca/sup 2 +/.

• Research Organization: Univ. of Puerto Rico, San Juan
• OSTI ID: 5411155
• Journal Information: Res. Commun. Chem. Pathol. Pharmacol.; (United States), Journal Name: Res. Commun. Chem. Pathol. Pharmacol.; (United States) Vol. 47:1; ISSN RCOCB
• Country of Publication: United States
• Language: English

Related Subjects

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59 BASIC BIOLOGICAL SCIENCES
ALKALI METAL COMPOUNDS
ALKALI METAL ISOTOPES
ALKALINE EARTH ISOTOPES
ALKALINE EARTH METAL COMPOUNDS
ANIMAL CELLS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BETA-PLUS DECAY RADIOISOTOPES
BIOCHEMICAL REACTION KINETICS
BIOCHEMISTRY
BIOLOGICAL PATHWAYS
CALCIUM 45
CALCIUM COMPOUNDS
CALCIUM ISOTOPES
CARBOHYDRATES
CARDIAC GLYCOSIDES
CARDIOTONICS
CARDIOVASCULAR AGENTS
CATIONS
CHARGED PARTICLES
CHEMISTRY
DAYS LIVING RADIOISOTOPES
DRUGS
EVEN-ODD NUCLEI
GLYCOSIDES
INTERMEDIATE MASS NUCLEI
IONS
ISOTOPES
KINETICS
LIGHT NUCLEI
LIVER CELLS
MAMMALS
MEMBRANE TRANSPORT
NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
OUABAIN
RADIOISOTOPES
RATS
REACTION KINETICS
RODENTS
SODIUM 22
SODIUM COMPOUNDS
SODIUM ISOTOPES
SOMATIC CELLS
STROPHANTHINS
VERTEBRATES
YEARS LIVING RADIOISOTOPES