Fig. 3.
Patch clamp recordings of right human auricle cardiomyocytes. (A), Right auricle cardiomyocytes were injected with a small negative current of about −20 pA in order to hyperpolarize the cells to −80 m V. Action potentials were elicited by injection of a 2 − 5 ms current pulse of 2 nA amplitude. Action potentials were evoked with a frequency of 1 Hz. After action potential duration reached a steady state (black), 2 µM A293 was administered, until steady-state was reached (grey). (B), Relative increase in APD50 and APD90 by 2 µM A293. (C), Dynamic patch clamp experiments of single myocytes were performed as previously described [37]. Right human auricle cardiomyocytes were held in current clamp mode and resting membrane potential was adjusted to −80 mV via the injection of a negative offset current, as described above. Action potentials were elicited at a frequency of 1 Hz via injection of a positive current pulse (2 − 3 nA) of 2 ms duration. Dynamic patch clamp experiments with subtraction of ITASK-1 led to prolonged action potential (dark grey line), injection of an additional ITASK-1 shortened APD (light grey line). (D), Bar graph showing prolongation of APD50 and APD90, respectively after subtraction of ITASK-1. (E), Shortening of APD50 and APD90 after injecting additional ITASK-1.