Figure 7. The effect of replacing 1.5 mm ${\text{Ca}}_{\text{o}}^{2+}$ by 1.5 mm ${\text{Ba}}_{\text{o}}^{2+}$ on the properties of single cation channel currents.

A, effects of replacing 1.5 mm ${\text{Ca}}_{\text{o}}^{2+}$ by 1.5 mm ${\text{Ba}}_{\text{o}}^{2+}$ on single cation currents recorded from the same patch at −50 mV. B, I–V relationship of the single cation currents shown in A in 1.5 mm ${\text{Ba}}_{\text{o}}^{2+}$ had a unitary conductance of 20 pS and an extrapolated V_r of +11 mV. C, the open time distribution of the single channel currents shown in A could be described by two exponentials with time constants of 1.4 ms (O_τ1) and 7 ms (O_τ2). D, the burst duration distribution of the single channel currents shown in A could be described by two exponentials with time constants of 2.6 ms (B_τ1) and 19 ms (B_τ2)