Aims: The sensation of bladder fullness (SBF) is triggered by the release of ATP. Therefore, the aim of this study was to investigate whether time-dependent changes in the levels of stretch-released ATP in mouse primary-cultured urothelial cells (MPCUCs) is regulated by circadian rhythm via clock genes.
Methods: MPCUCs were derived from wild-type and Clock mutant mice (ClockΔ19/Δ19 ), presenting a nocturia phenotype. They were cultured in elastic silicone chambers. Stretch-released ATP was quantified every 4 h by ATP photon count. An experiment was also performed to determine whether ATP release correlated with the rhythm of the expression of Piezo1, TRPV4, VNUT, and Connexin26 (Cx26) in MPCUCs regulated by clock genes with circadian rhythms. MPCUCs were treated with carbenoxolone, an inhibitor of gap junction protein; were derived from VNUT-KO mice; or treated with Piezo1-siRNA, TRPV4-siRNA, and Cx26-siRNA.
Results: Stretch-released ATP showed time-dependent changes in wild-type mice and correlated with the rhythm of the expression of Piezo1, TRPV4, VNUT, and Cx26. However, these rhythms were disrupted in ClockΔ19/Δ19 mice. Carbenoxolone eliminated the rhythmicity of ATP release in wild-type mice. However, time-dependent ATP release changes were maintained when a single gene was deficient such as VNUT-KO, Piezo1-, TRPV4-, and Cx26-siRNA.
Conclusions: ATP release in the bladder urothelium induces SBF and may have a circadian rhythm regulated by the clock genes. In the bladder urothelium, clock gene abnormalities may disrupt circadian ATP release by inducing Piezo1, TRPV4, VNUT, and Cx26. All these genes can trigger nocturia.
Keywords: ATP release; circadian rhythm; clock genes; cultured urothelial cells; nocturia; sensation of bladder fullness.
© 2018 Wiley Periodicals, Inc.