ISSN:
0021-9541
Schlagwort(e):
Life and Medical Sciences
;
Cell & Developmental Biology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Biologie
,
Medizin
Notizen:
The kinetics of Cl--SO4-2 exchange in Ehrlich ascites tumor cells was investigated in an attempt to determine the stoichiometry of this process.When tumor cells, equilibrated in Cl--free, 25 mM SO4-2 medium are placed in SO4-2-free, 25 mM Cl- medium, both the net amount and rate of Cl- uptake far exceeds SO4-2 loss. Addition of the anion transport inhibitor SITS (4-acetamido-4′-isothiocyano-stilbene-2,2′-disulfonic acid) greatly reduces sulfate efflux (97%), but has no measurable effect on chloride uptake. Addition of furosemide, a Cl- transport inhibitor, reduces chloride uptake 94% but is without effect on sulfate efflux. These findings suggest that a chloride permeability pathway exists distinct from that utilized by SO4-2.SITS, when added to furosemide treated cells, further reduces chloride uptake as well as inhibiting sulfate efflux, and under these experimental conditions, a linear relationship exists between SITS-sensitive, net chloride uptake and sulfate loss. The slope of this line is 1.05 (correlation coefficient = 0.996) which suggests the stoichiometry of Cl--SO4-2 exchange is 1:1. Assuming a 1:1 stoichiometry, measurement of the initial chloride influx and initial sulfate efflux indicate that 92% of net chloride uptake is independent of sulfate efflux.Taken altogether, these results support the contention that the tumor cell possesses a permeability pathway which facilitates the exchange of one sulfate for one chloride. Under conditions where anion transport is not inhibited, this coupling is obscured by a second and quantitatively more important pathway for chloride uptake. This pathway is SITS-insensitive, although partially inhibited by furosemide.
Zusätzliches Material:
5 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/jcp.1040900317
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