Figure 5.

Effect of symmetric [K⁺] on single channel conductance in hSlo and hSlo-D292N channels. Single channel current recordings from inside-out patches of oocytes expressing hSlo (A) and hSlo-D292N (B) are shown in various symmetrical [K⁺] in contaminant Ca²⁺. The current is elicited with 40-ms steps to +50 mV (A and B) and −50 mV (D) from 0-mV holding potential. The patch in B contains at least three channels. Note in D inward channel openings in hSlo-D292N at −50 mV and 700 mM symmetrical [K⁺]. Linear components were subtracted using traces without channel openings. (C and E) Single channel I–V curves for hSlo and hSlo-D292N, respectively. No inward single channels were detected in hSlo-D292N in 50 (□) or 200 (▵) mM K⁺. (F) Single channel conductance vs. [K⁺] plot for hSlo (○) and hSlo-D292N (□) channels. The single channel conductance was estimated from the linear range of the I–V relationship between +50 and +100 mV. The ionic strength of the solution was not kept constant, but increased with [K⁺].