Forskolin enhances the Ca²⁺ exchanger current. (A) Light-insensitive tail of the ROS current in responses to bright saturating flashes is well-reproducible. Three traces in each group are individual responses to three 10-ms flashes of ascending intensities that resulted in a >10-s saturation time (2,270, 3,880, and 6,610 photons · µm⁻²). Dark current was 20.7 pA in normal Ringer’s solution and 21.9 pA in forskolin solution. Recordings labeled forsk were done between 16 and 18 min after the start of forskolin perfusion. (B) Exchanger currents in forskolin solution and normal Ringer’s solution can be made congruent by amplitude scaling. Thin noisy lines are averages of corresponding three traces in A. Bold noisy line shows the current in forskolin solution downscaled by 1.68-fold to match the current recorded in normal Ringer’s solution. The scaling factor was found by maximizing the cross-correlation coefficient between the two curves. The heavy smooth line is a single-exponential approximation of averaged normal and downscaled forskolin responses. Fraction of the exchanger current, 0.062; decay time constant, 0.91 s.