Functional roles for K V 7.2 and K V 7.3 channels in guinea pig urinary bladder smooth muscle revealed by the novel K V 7.2/K V 7.3 channel opener ICA‐069673

Abstract

We elucidated the physiological role of KV7.2/KV7.3 channels in guinea pig urinary bladder smooth muscle (UBSM) in vitro using the novel KV7.2/KV7.3 channel opener ICA-069673 and a multidisciplinary experimental approach. Western blot revealed protein expression for KV7.2 and KV7.3 channels in UBSM. In isolated UBSM cells, immunocytochemistry detected protein expression of KV7.2 and KV7.3 channels with localization at the cell membrane. ICA-069673 caused a concentration-dependent (100 nM-30 µM) inhibition of spontaneous phasic, pharmacologically-induced, and nerve-evoked contractions in UBSM isolated strips. In solution with elevated K+ concentration (60 mM), the inhibitory effects of ICA-069673 on UBSM contractility were attenuated. ICA-069673 decreased the global intracellular Ca2+ concentration in UBSM cells, an effect blocked by the L-type voltage-gated Ca2+ channel inhibitor nifedipine (1 µM). ICA-069673 significantly hyperpolarized the membrane potential and inhibited spontaneous action potentials in UBSM cells measured with perforated patch-clamp. XE991 (10 µM), a Kv7 channel inhibitor, abolished the effects of ICA069673 on USBM contractility and membrane potential. These results establish KV7.2/KV7.3 channels as critical regulators of UBSM excitability and contractility. Supported by NIH R01DK04284 to Georgi V. Petkov & NIH F31DK104528 to Aaron Provence.