Figure 2. Whole-cell currents and reversal potentials (V_rev) measured from either Kir6.1- or Kir6.1-CFTR-transfected cells in the presence of various [K⁺]_o.

Two sets of traces from either Kir6.1- (Aa) or Kir6.1-CFTR-transfected cells (Ba) at three different extracellular [K⁺]_o. Arrowheads indicate the zero current level. Amplitudes of membrane currents were plotted against test potentials between −140 mV and +60 mV (Ab and Bb; 2.7 mm, ^; 5.4 mm, •; 20 mm, ▿; and 140 mm, ▾). V_rev values were measured as the x-intercept and are plotted against [K⁺]_o (Ac and Bc; means ±s.d.). Straight lines were drawn by fitting to the equation: V_rev= (RT/F)ln([K⁺]_o/[K⁺]_i), where R is the universal gas constant, T is absolute temperature and F is Faraday's constant. Numbers in parentheses indicate the number of observations.