Figure 2.

Protein kinase A (PKA)-dependent regulation of endogenous Kv7.5 currents in cultured HASMCs. (A) Representative current traces recorded in a single HASMC (Capacitance = 281 pF) before (i. control) and 5 min after addition of 10 µM retigabine (ii). (B) Mean fractional conductance plot calculated from steady-state endogenous Kv7 currents fitted to a Boltzmann distribution (V_0.5 = −40.8 mV, n = 10). (C) I–V relationships of Kv7 currents recorded in HASMCs before (control, filled circles, n = 5), after 5 min treatment with 1 µM forskolin (open circles, n = 4), and after 5 min treatment with diclofenac (100 µM, open triangles, n = 4). (D) I–V relationships of Kv7 currents recorded in HASMCs before (control, filled circles, n = 7), after 5 min treatment with 1 nM formoterol (open circles, n = 7), and after 5 min treatment with Kv7 channel blocker XE991 (1 µM) in the presence of 1 nM formoterol (closed triangles, n = 3). (E) Representative time-courses of 1 nM formoterol application recorded at −20 mV in a single untreated HASMC (black, Capacitance = 39 pF) and a HASMC pretreated with 10 µM H-89 (red, C = 127 pF). (F) Relative formoterol-induced enhancement of the current recorded at −20 mV in untreated HASMCs (black bars, n = 7) and in HASMCs pretreated with H-89 (10 µM for 20 min, red bar, n = 4). * Significant difference from control (p < 0.01, Mann-Whitney Rank Sum Test).