FIGURE 6.
Dominant-negative inhibition of IKCa currents by hKCa3.1 spliced variants in the Xenopus oocyte expression system. Human KCa3.1 spliced variants were expressed in Xenopus oocytes by injection of the corresponding cRNA. A, representative traces from oocytes injected with the cRNA for hKCa3.1a. Ionomycin- and DC-EBIO-activated and ChTX-inhibited currents were studied by two-electrode voltage clamp. Current to voltage relations were derived by voltage ramp protocols under physiological conditions. B–D, co-expression of hKCa3.1b (B), hKCa3.1c (C), and hKCa3.1d (D) with hKCa3.1a largely reduced hKCa3.1a-induced IKCa currents. Current amplitudes were measured at −30 mV. Oocytes were injected with the cRNA for hKCa3.1a and hKCa3.1b/c/d at 1:0, 1:1, 1:10, and 0:1 ratios as indicated. Means ± S.E. of current amplitudes from 3 to 8 oocytes for each condition. *, **, p < 0.05, 0.01, significantly different as determined by Tukey's test.