Figure 6.
TEA blocks IK,slow and Iss in adult mouse ventricular myocytes. Outward currents were recorded as described in Fig. 1 during 4.5-s depolarizing voltage steps to −20 to +60 mV from a holding potential of −70 mV; records from two cells exposed to 25 (A–C) or 135 (D–F) mM are presented. In each example, control currents (A and D) were recorded before application of TEA; cells were the exposed to 25 or 135 mM TEA, and when the effect (of TEA) reached steady state, the currents in the presence of 25 (B) or 135 (E) mM TEA were recorded. In B and E, the currents in the presence of 4-AP are plotted as solid lines, and the control records (A and D, respectively) are replotted as points to facilitate comparison. The waveforms of the 25-mM (C) and 135-mM (F) TEA-sensitive currents were obtained by off-line digital subtraction of the currents in the presence of TEA from the controls. Similar results were obtained in experiments on three (25 mM TEA) or four (135 mM TEA) cells. Scale bars, 2 nA and 500 ms.