Bk(Ca) channel activity enhances with muscle stretch in guinea-pig urinary bladder smooth muscle.
Possible effects of muscle stretch on the spontaneous rhythmic contractile activity and the extent of contribution of voltage-dependent and Ca2+ -activated K+ (BK(Ca)) channels were examined mechanically in guinea-pig urinary bladder smooth muscle (UBSM). The amplitude of the spontaneous mechanical activity showed stretch-dependency. Iberiotoxin, a selective blocker of BK(Ca) channels, potently increased contraction amplitude, and this effect was more prominent when muscle length was more than twice of its initial length. BK(Ca) channels seem activated more strongly to counteract enhanced spontaneous mechanical activity with UBSM stretch.
Tanaka
Yoshio
Y
Department of Chemical Pharmacology, Toho University School of Pharmaceutical Sciences, 2-2-1 Miyama, Funabashi-City, Chiba 274-8510, Japan. yotanaka@phar.toho-u.ac.jp
Okamoto
Takao
T
Imai
Toshiyasu
T
Yamamoto
Yoshihisa
Y
Horinouchi
Takahiro
T
Tanaka
Hikaru
H
Koike
Katsuo
K
Shigenobu
Koki
K
D000818:Animals; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects*; D005260:Female; D006168:Guinea Pigs; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D010455:Peptides / Q000494:pharmacology*; D001743:Urinary Bladder / Q000187:drug effects
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D010455:Peptides; C064719:iberiotoxin