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BioMed Research International
Volume 2016 (2016), Article ID 9497041, 11 pages
Research Article

Role of BKCa in Stretch-Induced Relaxation of Colonic Smooth Muscle

1Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China
2Yanjing Medical College, Capital Medical University, Beijing 101300, China

Received 22 July 2016; Revised 30 September 2016; Accepted 23 October 2016

Academic Editor: Christina Pabelick

Copyright © 2016 Jie Ren et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Stretch-induced relaxation has not been clearly identified in gastrointestinal tract. The present study is to explore the role of large conductance calcium-activated potassium channels (B) in stretch-induced relaxation of colon. The expression and currents of B were detected and the basal muscle tone and contraction amplitude of colonic smooth muscle strips were measured. The expression of B in colon is higher than other GI segments (P < 0.05). The density of B currents was very high in colonic smooth muscle cells (SMCs). B in rat colonic SMCs were sensitive to stretch. The relaxation response of colonic SM strips to stretch was attenuated by charybdotoxin (ChTX), a nonspecific B blocker (P < 0.05). After blocking enteric nervous activities by tetrodotoxin (TTX), the stretch-induced relaxation did not change (P > 0.05). Still, ChTX and iberiotoxin (IbTX, a specific B blocker) attenuated the relaxation of the colonic muscle strips enduring stretch (P < 0.05). These results suggest stretch-activation of B in SMCs was involved in the stretch-induced relaxation of colon. Our study highlights the role of mechanosensitive ion channels in SMCs in colon motility regulation and their physiological and pathophysiological significance is worth further study.