Figure 8.

Unitary Ba²⁺ currents recorded in cell-attached patches of pig urethral myocytes. The pipette was filled with 90 mM Ba²⁺ solution and 142 mM K⁺ solution was superfused in the bath. (a) The unitary Ba²⁺ currents were obtained using a depolarizing pulse (400 ms duration, 10 s interval) from a holding potential of −90 mV to the indicated membrane potential (from −40 mV to +20 mV). The average currents from 10 null traces (the nearest five traces before and after the event in which the channel did not open) were subtracted. The dashed line indicates the current base line where the channel is not open. (b) Current-voltage relationships of the unitary Ba²⁺ current obtained from −40 mV to +20 mV. The amplitude of the Ba²⁺ channel currents was taken from the all-points amplitude histograms at each depolarizing potential. The line was fitted by the least-squares method. The channel conductance was 27 pS (27.3±1.9 pS, n=8).