Mechanisms of chloride transport in thymic lymphocytes

Donatas Stakisaitis, Michael S. Lapointe, Daniel Batlle
2001 AJP - Renal Physiology  
Stakisaitis, Donatas, Michael S. Lapointe, and Daniel Batlle. Mechanisms of chloride transport in thymic lymphocytes. Am J Physiol Renal Physiol 280: F314-F324, 2001.-This study examined mechanisms of Cl Ϫ transport in rat lymphocytes under a variety of conditions. Basal intracellular Cl Ϫ concentration ([Cl Ϫ ] i ) was not different between cells assayed in the presence of HCO 3 Ϫ or its absence (HEPES). Removal of external Cl Ϫ resulted in a fall in [Cl Ϫ ] i and a rapid rise in intracellular
more » ... pH (pH i ). Both Cl Ϫ efflux and the rise in pH i were blocked by DIDS or removal of external Na ϩ but were unaffected by furosemide. The mechanisms governing Cl Ϫ influx were assessed in cells that had been Cl Ϫ depleted for 1 h. Reexposure to Cl Ϫ resulted in a rapid rise in [Cl Ϫ ] i that was partially inhibited by pretreatment with DIDS (57%) and partially inhibited by pretreatment with furosemide (45%). Pretreatment with both compounds together completely blocked Cl Ϫ influx. Cl Ϫ depletion caused a marked increase in pH i that rapidly declined toward normal when the cells were reexposed to Cl Ϫ . Preincubation with DIDS completely blocked this decrease in pH i . In contrast, neither removal of Na ϩ nor preincubation with furosemide affected the decline in pH i when the cells were reexposed to Cl Ϫ . We conclude that, in thymic lymphocytes, Cl Ϫ /HCO 3 Ϫ (or Cl Ϫ /base exchange) regulates both Cl Ϫ influx and efflux. Cl Ϫ efflux is totally inhibited by DIDS and is mediated by a Na ϩ -dependent Cl Ϫ /HCO 3 Ϫ exchanger. Cl Ϫ influx is partially DIDS sensitive and partially furosemide sensitive and is mediated by both a Na ϩ -independent Cl Ϫ /HCO 3 Ϫ exchanger and by a Na ϩ -K ϩ -2Cl Ϫ cotransporter. chloride/bicarbonate exchange; sodium-potassium-2 chloride
doi:10.1152/ajprenal.2001.280.2.f314 pmid:11208607 fatcat:jcgihrx77ve5fmkecbgoaktnt4