Effects of new-generation TMEM16A inhibitors on calcium-activated chloride currents in rabbit urethral interstitial cells of Cajal.

Abstract

Interstitial cells of Cajal (ICC) isolated from the rabbit urethra exhibit Ca2+-activated Cl- currents (I ClCa) that are important for the development of urethral tone. Here, we examined if TMEM16A (ANO1) contributed to this activity by examining the effect of "new-generation" TMEM16A inhibitors, CACCinh-A01 and T16Ainh-A01, on I ClCa recorded from freshly isolated rabbit urethral ICC (RUICC) and on contractions of intact strips of rabbit urethra smooth muscle. Real-time quantitative PCR experiments demonstrated that TMEM16A was highly expressed in rabbit urethra smooth muscle, in comparison to TMEM16B and TMEM16F. Single-cell RT-PCR experiments revealed that only TMEM16A was expressed in freshly isolated RUICC. Depolarization-evoked I ClCa in isolated RUICC, recorded using voltage clamp, were inhibited by CACCinh-A01 and T16Ainh-A01 with IC50 values of 1.2 and 3.4 μM, respectively. Similarly, spontaneous transient inward currents (STICs) recorded from RUICC voltage clamped at -60 mV and spontaneous transient depolarizations (STDs), recorded in current clamp, were also inhibited by CACCinh-A01 and T16Ainh-A01. In contrast, spontaneous Ca2+ waves in isolated RUICC were only partially reduced by CACCinh-A01 and T16Ainh-A01. Finally, neurogenic contractions of strips of rabbit urethra smooth muscle (RUSM), evoked by electric field stimulation (EFS), were also significantly reduced by CACCinh-A01 and T16Ainh-A01. These data are consistent with the idea that TMEM16A is involved with CACCs in RUICC and in contraction of rabbit urethral smooth muscle.

• Authors: Stephen Fedigan, Eamonn Bradley, Timothy Webb, Roddy J Large, Mark A Hollywood, Keith D Thornbury, Noel G McHale, Gerard P Sergeant
• Journal: Pflugers Archiv : European journal of physiology (Pflugers Arch) Vol. 469 Issue 11 Pg. 1443-1455 (11 2017) ISSN: 1432-2013 [Electronic] Germany
• PMID: 28733893 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Anoctamin-1
• Chloride Channels
• Chlorides
• Calcium

Topics

• Animals
• Anoctamin-1 (antagonists & inhibitors)
• Calcium (metabolism)
• Cells, Cultured
• Chloride Channels (metabolism)
• Chlorides (metabolism)
• Female
• Interstitial Cells of Cajal (drug effects, metabolism)
• Male
• Membrane Potentials (drug effects)
• Muscle, Smooth (drug effects, metabolism)
• Rabbits
• Urethra (drug effects, metabolism)