Figure 3. Expression of Slick and Slack in CHO cells. Whole-cell recordings and associated current-voltage relationships of representative cells transfected with Slick (A) and Slack (B). Recordings were made in bath solutions containing (in mm): 5 NaCl, 140 KCl, 29 glucose, 1 CaCl2, and 25 HEPES, pH 7.4. The voltage protocol consisted of 200 msec steps from -120 to +120 mV in 20 mV increments from a holding potential of -70 mV. Pipette solution contained (in mm):130 KCl, 5 EGTA, and 10 HEPES, pH 7.2. C, Representative Slick-transfected cell under identical recording conditions as in B except that [Cl-] was reduced to 5 mm in the pipette solution by replacement with gluconate. D, Cl- sensitivity of Slick. Average current-density versus voltage of cells recorded in 130 mm Cl- (n = 5), 30 mm Cl- (n = 5), and 3 mm Cl- (n = 4). E, Single-channel properties of Slick and Slack (F) channels. Excised inside-out patches of transfected CHO cells were recorded in a symmetrical solution containing (in mm): 130 KCl, 5 Na-gluconate, 5 EGTA, 10 HEPES, and 29 glucose. All-points histograms for channel recordings are shown in insets. Subconductances for both Slack and Slick were often observed. Recordings were conducted at +80 mV. The “C” and “O” labels represent data from the closed and main open state, respectively. Arrows indicate subconductance states.