Ion conduction and selectivity in acid-sensing ion channel 1.

ABSTRACT: The ability of acid-sensing ion channels (ASICs) to discriminate among cations was assessed based on changes in conductance and reversal potential with ion substitution. Human ASIC1a was expressed in Xenopus laevis oocytes, and acid-induced currents were measured using two-electrode voltage clamp. Replacement of extracellular Na(+) with Li(+), K(+), Rb(+), or Cs(+) altered inward conductance and shifted the reversal potentials consistent with a selectivity sequence of Li ∼ Na > K > Rb > Cs. Permeability decreased more rapidly than conductance as a function of atomic size, with P(K)/P(Na) = 0.1 and G(K)/G(Na) = 0.7 and P(Rb)/P(Na) = 0.03 and G(Rb)/G(Na) = 0.3. Stimulation of Cl(-) currents when Na(+) was replaced with Ca(2+), Sr(2+), or Ba(2+) indicated a finite permeability to divalent cat

SUBMITTER: Yang L 

PROVIDER: S-EPMC4144671 | biostudies-literature | 2014 Sep

REPOSITORIES: biostudies-literature