| Autor: |
Skulskii, Igor A., Gusev, Gennadii P., Sherstobitov, Alexander O., Manninen, Vesa |
| Zdroj: |
Journal of Membrane Biology; December 1992, Vol. 130 Issue: 3 p219-225, 7p |
| Abstrakt: |
Unidirectional fluxes of 204Tl+ through the human red blood cell membrane were measured. The inward rate coefficient measured in a K+-free saline was 15.6±0.6 hr-1. The influx of Tl+ could be partially inhibited with 0.1mm ouabain (by 28%), 0.1mm DIDS (by 50%) or 1mm furosemide (by 51%). The inhibitory effects of ouabain and DIDS or furosemide were additive. Half-maximal responses were seen at 0.72 µm and 0.22mm concentrations of DIDS and furosemide, respectively. A similar action of these blockers on Tl+ influx was observed in the erythrocytes incubated in MgCl2-sucrose media. The outward rate coefficient of 204Tl was also inhibited by DIDS and furosemide (by 65 and 52%, respectively). Rate coefficients of 204Tl influx and efflux decreased significantly in the red cells exposed to Cl--free media (NaNO3 or Mg(NO3)2-sucrose). Under these conditions addition of DIDS and furosemide led to only a small inhibition of Tl+ fluxes. There was a linear increase in Tl+ influx with rising of external Cl- concentration within 80–155mm or HCO3-concentration from 20 to 40mm when the sum of anions was kept constant (155mm) with NO3-. The HCO3--stimulated Tl+ influx was completely blocked by 0.05mm DIDS but only 67% by 1mm furosemide. The present study provides direct evidence for the occurrence of Cl- (HCO3-)-dependent, DIDS-sensitive movement of Tl+ across the human erythrocyte membrane in both directions. Under physiological conditions, about half of net Tl+ fluxes occurs due to an anion exchange mechanism. Our data fail to detect a contribution of the Na-K-Cl cotransport system to Tl+ transport in human erythrocytes. |
| Databáze: |
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