Figure 6.

Effects of ZD6169 on voltage-dependent Ba²⁺ inward currents at a holding membrane potential of −50 mV in pig urethra. The pipette solution was Cs⁺ – TEA⁺ solution containing 5 mM EGTA and the bath solution was 10 mM Ba²⁺ containing 135 mM TEA⁺. (a) (i) Original current traces before (control) and after application of 50 μM ZD6169 at the indicated pulse potentials. (ii) Inward Ba²⁺ current from (i) scaled to match their peak amplitudes and superimposed. (b) Current-voltage relationships obtained in the absence (control) or presence of 50 μM ZD6169. The current amplitude was measured as the peak amplitude of the Ba²⁺ inward current in each condition. The lines were drawn by eye. (c) Relationship between the test potential and relative value of the Ba²⁺ inward currents inhibited by 50 μM ZD6169, expressed as a fraction of the peak amplitude of the Ba²⁺ inward current evoked by various amplitude of the depolarizing pulse in the absence of ZD6169. Each symbol indicates the mean of four observations with±s.d. shown by vertical lines. The line was drawn by eye.