To investigate the changes including expression and localization of two potassium channels, renal outer medullary K(+) channel (ROMK) and voltage-gated K(+) channel 7.1 (KCNQ1), after increased urinary potassium leakage in patients with interstitial cystitis/painful bladder syndrome (IC/PBS).
The study group included 24 patients with IC/PBS and a control group consisting of 12 volunteers without any IC/PBS symptoms. Bladder biopsies were taken from both groups. We determined the protein expression and distribution of potassium channels using immunoblotting, immunohistochemistry, and immunofluorescent staining under confocal laser microscopy.
The results revealed that ROMK was predominantly expressed in apical cells of the bladder urothelium at significantly higher levels (3.3-fold) in the study group than in the control group. In contrast, KCNQ1 was expressed in the basolateral membrane according to confocal microscopy results and did not significantly differ between groups.
Our data showed that the abundance of ROMK protein in apical cells was increased in IC/PBS group, whereas KCNQ1, which was distributed in the basolateral membrane of the bladder urothelium, showed similar abundance between groups. These results suggest that upregulation of the ROMK channel in apical cells might permit avid potassium flux into the bladder lumen to maintain intracellular K(+) homeostasis in the dysfunctional urothelium.
Urology. 2016 Jan 14 [Epub ahead of print]
Jane-Dar Lee, Ming-Huei Lee, Wen-Kai Yang, Kuan-Lin Wang, Tsung-Han Lee
Department of Surgery, Kaohsiung Veterans General Hospital, Kaohsiung 813, Taiwan, Republic of China; Central Taiwan University of Science and Technology, Taichung 406, Taiwan, Republic of China; Division of Urology, Department of Surgery, Taichung Armed Forces General Hospital, Taichung 411, Taiwan, Republic of China. Electronic address: ., Department of Urology, Feng-Yuan Hospital, Ministry of Health and Welfare, Taichung 420, Taiwan, Republic of China., Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan, Republic of China; Bachelor Degree Program in Animal Healthcare, Hungkuang University, Taichung 433, Taiwan, Republic of China., Department of Life Sciences, National Chung Hsing University, Taichung 402, Taiwan, Republic of China.