Figure 15.
Effects of Anti-ClC-2 Ab on pacemaker action potential in SAN cells. (A) Representative spontaneous action potentials recorded from an SAN cell by current-clamp (no current injection) with pipette solution containing no anti-ClC-2 Ab under isotonic (a) and hypotonic (b) conditions. SAN cells were exposed to isotonic solution for at least 10 min before action potential recordings. Action potentials shown in panel a were recorded right after successful whole-cell configuration under isotonic conditions. Action potentials shown in panel b were recorded after exposure to hypotonic solution for 20 min. For comparison, the action potentials recorded under these conditions were superimposed with an expanded time scale in panel c. The dotted lines indicate zero voltage. (B) Spontaneous action potentials recorded from a SAN cell by current clamp using a pipette solution containing pre-absorbed anti-ClC-2 Ab (control) and cell was exposed to isotonic solutions for 10 min (a) and hypotonic solutions for 20 min (b). For comparison, the action potentials recorded under these conditions were superimposed with an expanded time scale in panel c. (C) SAN cells were perfused with isotonic solutions for 20 min before whole-cell recordings. Action potentials were recorded immediately after membrane rupture (a) and after dialysis of anti-ClC-2 Ab for 20 min (b) under the same isotonic conditions. Panel c shows the expanded and superimposed action potentials as shown in panel a and panel b. Note that after 20 min dialysis of anti-ClC-2 Ab in to the cell the spontaneous action potential rate was not significantly altered. (D) SAN cells were exposed to hypotonic solution for 20 min to fully activate ICl,ir before whole-cell recordings. Action potentials were recorded immediately after membrane rupture (a) and after dialysis of anti-ClC-2 Ab for 20 min (b). Panel c shows the expanded and superimposed action potentials as shown in panel a and panel b. Note that the spontaneous action potential rate significantly decreased after 20 min dialysis of anti-ClC-2 Ab in to the cell, which corresponds with the decrease in inward