Novel outwardly rectifying anion conductance in Xenopus oocytes Article uri icon

abstract

  • We describe a novel, strongly outwardly rectifying anion current in Xenopus laevis oocytes, that we have named ICl,Or. The properties of I Cl,Or are different from those of any other anion conductance previously described in these cells. Typically, ICl,Or amplitude was small when extracellular Cl- (Cle) was the permeant anion. However, when Cle was replaced by lyotropic anions ICl,Or became evident as a time-independent current. ICl,Or was voltage dependent and showed a remarkable outwards rectification with little or no inwards tail current. The relative selectivity sequence determined from current amplitudes was: SCN-≥ ClO4->I ->Br-≥NO3->Cl-. ICl,Or was insensitive to Gd3 but was blocked by micromolar concentrations of niflumic acid, DIDS or Zn2 . Furthermore, ICl,Or was not affected by buffering intracellular Ca2 with BAP-TA. Low extracellular pH inhibited ICl,Or with a pK of 5.8. We propose that ICl,Or might result from activation of endogenous ClC-5-like Cl- channels present in Xenopus oocytes. © Springer-Verlag 2004.
  • We describe a novel, strongly outwardly rectifying anion current in Xenopus laevis oocytes, that we have named ICl,Or. The properties of I Cl,Or are different from those of any other anion conductance previously described in these cells. Typically, ICl,Or amplitude was small when extracellular Cl- (Cle) was the permeant anion. However, when Cle was replaced by lyotropic anions ICl,Or became evident as a time-independent current. ICl,Or was voltage dependent and showed a remarkable outwards rectification with little or no inwards tail current. The relative selectivity sequence determined from current amplitudes was: SCN-≥ ClO4->I ->Br-≥NO3->Cl-. ICl,Or was insensitive to Gd3%2b but was blocked by micromolar concentrations of niflumic acid, DIDS or Zn2%2b. Furthermore, ICl,Or was not affected by buffering intracellular Ca2%2b with BAP-TA. Low extracellular pH inhibited ICl,Or with a pK of 5.8. We propose that ICl,Or might result from activation of endogenous ClC-5-like Cl- channels present in Xenopus oocytes. © Springer-Verlag 2004.

publication date

  • 2004-01-01