Urothelial Piezo1 channels do not alter voiding or afferent nerve sensitivity in the mouse

Abstract

The mechanosensitive piezo ion channels, Piezo1 and Piezo2, are expressed in tissues of the lower urinary tract, including the urothelium and sensory nerves. Interest in a role of piezo mechanosensitive ion channels in mediating sensory physiology in the lower urinary tract has been highlighted by the recent reports of putative voiding dysfunction in mice lacking Piezo2 channels in the lower extremities and sensory nerves (Marshall et al 2020) and Piezo1/2 in urothelium (Dalghi et al 2022). To investigate the potential role of urothelial Piezo1 channels in mediating normal function in the lower urinary tract, we generated a mouse line in which the Piezo1 gene can be conditionally knocked out in the urothelium (Piezo1UPKcKO mice). We examined spontaneous voiding behavior in male and female Piezo1UPKcKO and control mice during the light and dark phases of the day/night cycle. There were no gender differences in voiding parameters in our study (p=0.659, 3-way ANOVA), thus we did not isolate gender as a variable for further analysis. Piezo1UPKcKO mice (n=9) voided 6 ± 1 times per 24 hours, while the control mice (n=11) voided 7 ± 1 times per 24 hours (p = 0.7281). A clear nocturnal voiding pattern was observed with both Piezo1UPKcKO and control mice exhibiting more frequent voids during the dark cycle, but there were no differences in the number of voids, intermicturition intervals, or void volumes in any cycle between Piezo1UPKcKO and control mice. These results indicate that spontaneous voiding behavior remains fully intact in both male and female Piezo1UPKcKO mice during the light and dark phases of the day/night cycle. Furthermore, in an ex vivo bladder model where we measure afferent nerve output from the bladder during filling cycles, sensory nerve activity in the Piezo1UPKcKO mice was similar to that in bladders from control animals. The maximum frequency of afferent nerve activity during bladder filling reached 295 ± 28 Hz in control mice (n=6) and 336 ± 34 Hz in Piezo1UPKcKO mice (n=6; p = 0.368). Functional Piezo1 activity could be demonstrated in bladders from both Piezo1UPKcKO and control mice, as the pharmacological activator for Piezo1 channels, Yoda1 (5 μM) increased maximum afferent nerve activity during bladder filling by 60 ± 15 Hz in control mice (P = 0.0029) and 33 ± 15 Hz in Piezo1UPKcKO mice (P = 0.0567). In Ca2+ imaging experiments, we found that Yoda1 induced an increase in Ca2+ signaling events in urothelial tissue from control mice. Thus, it appears that urothelial cells express functional Piezo1 ion channels, but activity of these channels is not required for maintaining normal sensory nerve activity and voiding behavior. This work was supported by a grant from the National Institute of Diabetes and Digestive and Kidney Diseases (R01DK125543). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.