FIGURE 4.

Knockdown of Hap1 reduces L-type Ca²⁺ currents in INS-1 cells. INS-1 cells were transfected with Hap1-siRNA or scramble-siRNA plasmids. Whole cell L-type Ca²⁺ currents were measured using Ba²⁺ as the charge carrier. A, representative L-type Ca²⁺ current traces from scramble-siRNA (middle traces) or Hap1-siRNA (bottom traces) groups. Cells were held at a holding potential of −70 mV and stepped from −60 to +50 mV in 10-mV increments. B, mean current-voltage relations of L-type Ca²⁺ currents recorded from INS-1 cells transfected with Hap1-siRNA (▴) or scramble-siRNA (●). C, averaged peak L-type current density recorded from INS-1 cells transfected with Hap1-siRNA or scramble-siRNA plasmids at +10 mV. Ba²⁺ currents were elicited by 200-ms pulses to 0 mV from a V-h of −70 mV (**, p < 0.001, scramble n = 21, siRNA n = 21).