Figure 6. Single-channel recordings of Ca²⁺-activated K⁺ channels in PDEC.

A, channel activity recorded at different intracellular (bath) Ca²⁺ concentrations in an excised inside-out patch. Bars indicate application of Ca²⁺ in the bath solution. Between tests, the bath solution contained 5 mm EGTA without Ca²⁺. Patches were held at −100 mV with 120 mm K⁺ on both sides. Bottom panels represent expanded traces of the regions marked by asterisks. Dashed line and arrowhead denote the closed state of the channels. B, dose–response relation. Normalized P_open is plotted as a function of the Ca²⁺ concentration (2–7 patches for each point). The curve was obtained by fitting the data points with the Hill equation (see Data analysis).