Figure 10.

Effects of quinidine and clofilium upon the hyperpolarizing K⁺ current and the CatSper-dependent Cs⁺ current. In all experiments, membrane currents were induced by a series of voltage ramps (−92 mV to 68 mV, 5 s), and the currents flowing during the final part of each ramp then quantified as a read out of the outward current flowing at 65–68 mV (I_Out). The left-hand part of each figure (i) shows the changes in I_Out induced by 1 min exposure to the test substances. The right-hand panels show I_m–V_m relationships constructed using data recorded under standard conditions at the onset of the experiment (Control), once the inhibitory effect of the test substances were fully established and after the drug had been washed from the bath by 5 min superfusion with standard bath solution (Wash). (A) Quinidine-induced (0.3 mM) block of the hyperpolarizing K⁺ current (n = 5). (B) Clofilium-induced block of the hyperpolarizing K⁺ current (n = 5). (C) Quinidine (0.3 mM) induced block of the CatSper-dependent Cs⁺ current (n = 5). (D). Clofilium-induced block of the CatSper-dependent Cs⁺ current (n = 5). All data are mean ± s.e.m.