Figure 4.

Soft substrate increases the BK channel currents in ventricular myocytes and HEK293 heterologously expressing the stretch-activated BK channel. (A) Representative whole-cell recordings of outward K⁺ currents from cells on the soft and stiff substrates before (left panels), and 10 min after, application of 100 nM IBTX (middle panels) and IBTX-sensitive currents (right panels). (B) Mean I-V relationships of the IBTX-sensitive currents from 10 cells in three preparations for each case. (C) Representative whole-cell recordings of outward K⁺ channel currents from HEK293 cells heterologously expressing the BK channel STREX-containing α- and β₁-subunits and cultured on the soft and stiff substrates before (left panels), and 10 min after, application of 100 nM IBTX (middle panels) and IBTX-sensitive current (right panels). (D) Mean I-V relationships of the IBTX-sensitive current in 11 cells from three preparations for each case. ^∗p < 0.05, comparison to the current density at the same voltage.