title: Role of BKCain Stretch-Induced Relaxation of Colonic Smooth Muscle.
abstract: 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 (BKCa) in stretch-induced relaxation of colon. The expression and currents of BKCawere detected and the basal muscle tone and contraction amplitude of colonic smooth muscle strips were measured. The expression of BKCain colon is higher than other GI segments (P< 0.05). The density of BKCacurrents was very high in colonic smooth muscle cells (SMCs). BKCain rat colonic SMCs were sensitive to stretch. The relaxation response of colonic SM strips to stretch was attenuated by charybdotoxin (ChTX), a nonspecific BKCablocker (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 BKCablocker) attenuated the relaxation of the colonic muscle strips enduring stretch (P< 0.05). These results suggest stretch-activation of BKCain 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.
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China.
authors.forename: Jie
authors.identifier: 0000-0002-9711-7349
authors.initials: J
authors.lastname: Ren
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China.
authors.forename: Fang
authors.identifier: 0000-0002-5100-9633
authors.initials: F
authors.lastname: Xin
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Liu
authors.affiliation: Yanjing Medical College, Capital Medical University, Beijing 101300, China.
authors.forename: Hai-Yan
authors.identifier: 0000-0002-8125-1375
authors.initials: HY
authors.lastname: Zhao
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China.
authors.forename: Si-Tao
authors.identifier: 0000-0003-4330-5931
authors.initials: ST
authors.lastname: Zhang
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China.
authors.forename: Peng
authors.identifier: 0000-0002-2013-9435
authors.initials: P
authors.lastname: Han
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China.
authors.forename: Hai-Xia
authors.identifier: 0000-0001-8481-7277
authors.initials: HX
authors.lastname: Huang
authors.affiliation: Department of Physiology and Pathophysiology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, China.
authors.forename: Wei
authors.identifier: 0000-0003-1537-8471
authors.initials: W
authors.lastname: Wang
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D018999:Charybdotoxin / Q000378:metabolism; D003106:Colon / Q000187:drug effects / Q000502:physiology*; D055595:Mechanical Phenomena; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology*; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000502:physiology; D010455:Peptides / Q000008:administration & dosage; D051381:Rats; D013779:Tetrodotoxin / Q000008:administration & dosage
chemical_list: D010455:Peptides; D018999:Charybdotoxin; D013779:Tetrodotoxin; C064719:iberiotoxin; D002118:Calcium