[The role of the sodium gradient in the efflux of Ca++ ions from the smooth muscle cells of the ureter].
The role of sodium in calcium active transport from the ureter muscle, preliminarily enriched in these ions, was studied in large ouabain concentration (10(-4) mmol/l) for complete inhibition of the Na(+)-K(+)-pump. The determination of intracellular concentrations of sodium and calcium ions (by flame photometry and isotopic analysis, resp.) showed that a fast decrease of intracellular calcium content was accompanied by an increase of intracellular sodium. With high sodium ions concentration in medium (above 100 mmol/l), the velocity of the decrease in intracellular calcium content reached the maximal value, the efflux of additional enriched calcium ions occurring within 10-15 min. The decrease of intracellular calcium content was in sigmoidal dependence on the concentration of sodium ions in the medium. The electrogenic Na(+)-Ca(++)-exchange system seems to play a major role in calcium-enriched muscles for the decrease of intracellular calcium content.
Kazarian
K V
KV
Oganesian
A S
AS
Gevorkian
G A
GA
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D003864:Depression, Chemical; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007552:Isotonic Solutions; D009130:Muscle, Smooth / Q000187:drug effects / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D010477:Perfusion; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects; D013997:Time Factors; D014513:Ureter / Q000187:drug effects / Q000378:metabolism
D007552:Isotonic Solutions; C051865:Krebs-Ringer solution; D010042:Ouabain; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium
Rol' natrievogo gradienta v vyvedenii ionov Ca++ iz gladkomyshechnykh kletok mochetochnika.