Figure 2.

PCMBS increases steady-state P_o(max). Variance analysis of KCa3.1 channel current was used to estimate P_o(max), N, and i in the absence and presence of PCMBS. (A) Representative Ca²⁺ concentration response experiment recorded from inside-out macropatches expressing KCa3.1 channels. Patches were initially excised in 10 µM Ca²⁺_i, followed by a series of Ca²⁺_i concentrations (0, 0.1, 0.15, 0.2, 0.25, 0.3, 0.6, 1.0, and 10 µM) applied for 10-s intervals using a fast solution exchanger. After establishing steady-state current in 10 µM Ca²⁺_i, PCMBS (500 µM) was added to the bath solution until reaching a second, steady-state, current level. (B) Variance analysis to determine P_o(max), N, and i in the absence of PCMBS. Plot of variance (σ²), which was calculated from the portion of the record excluding the time when PCMBS was added, against mean current 〈I〉 as fit with Eq. 1 (solid line), and P_o(max) was calculated using Eq. 2: P_o(max) = 0.61, n = 1,071, and i = 3.5 pA. (C) Variance analysis to determine P_o(max), N, and i in the presence of PCMBS. Plot of σ², which was calculated from the entire record against 〈I〉 was fit with Eq. 1 (solid line), and P_o(max) was calculated using Eq. 2: P_o(max) = 0.91, n = 1,078, and i = 3.4 pA.