Functional implications of Kv7 channels expression in guinea pig urinary bladder smooth muscle contractility

Abstract

The physiological roles of Kv7 channel family have been well studied in various tissues. However, knowledge about the functional role of Kv7 channels in the urinary bladder smooth muscle (UBSM) is limited. We investigated Kv7 channels molecular expression in guinea pig UBSM and further assessed their functional role using isometric DSM tension recordings and Kv7 channels modulators. RT‐PCR experiments revealed mRNA expression for Kv7.1, Kv7.2, Kv7.3, Kv7.4, and Kv7.5 channel subunits in guinea pig UBSM tissue. Quantitative PCR analysis showed that in UBSM tissue, Kv7 channel subunits relative mRNA expression level was as follows: Kv7.1 ≈ Kv7.2 >; Kv7.3 ≈ Kv7.5 >; Kv7.4. Retigabine, a Kv7 channel activator, and L‐364,373, a selective Kv7.1 channel activator, induced relaxation of spontaneous phasic contraction amplitude, force integral, duration, and frequency as well as the 10 Hz electrical field stimulation (EFS)‐induced contractions amplitude and force of UBSM isolated strips (IC50 = 3 – 6 μM). Linopiridine and XE991, two well‐established Kv7 channel inhibitors, increased the spontaneous phasic contraction amplitude and force as well as the 10 Hz EFS‐induced contractions amplitude and force of UBSM isolated strips (IC50 = 3 – 4 μM). In summary, we revealed the expression and the regulatory role of Kv7 channels in the spontaneous and nerve‐evoked contractions of guinea pig UBSM. Supported by NIH DK084284 to GVP.