Fig. 3. Emergence of BSP-sensitive Maxi-Cl activity in C1300 cells by heterologous overexpression of Slco2a1 alone or together with Anxa2. A, B, C. The effects of overexpression of ANXA2 alone, SLCO2A1 alone, and SLCO2A1 together with ANXA2 on Maxi-Cl activity. The currents were recorded after patch excision from C1300 cells during repetitive application (every 5 s) of alternating test pulses (±25 mV for 0.5 s) from the holding potential (0 mV). Any Maxi-Cl activity was not observed in those transfected with Anxa2 alone (A) (n=7). In contrast, Maxi-Cl currents were observed in C1300 cells transfected with Slco2a1 alone (B) or together with Anxa2 (C). These time courses of channel activation after patch excision during application of alternating pulses are shown in a, and single representative traces recorded upon a single alternating pulse are shown in b. The circle marks a representative single-channel event with a large amplitude (B-b). Effects of BSP (50 μM) and washout of this drug are also shown in B-a. D. Summary of the effects of single overexpression of vector alone (Control) or SLCO2A1 alone (i) and double overexpression of vectors (Control) or SLCO2A1 plus ANXA2 (ii) on the mean Maxi-Cl currents recorded at +25 mV. Each column represents the mean ± SEM (vertical bar). *p<0.05 (Student's t-test) vs Control. **p<0.05 (Student's t-test) between the currents induced by double overexpression of SLCO2A1 plus ANXA2 and those induced by single overexpression SLCO2A1 alone.