Susumu Ohya, Shunichi Kimura, Mika Kitsukawa, Katsuhiko Muraki, Minoru
Watanabe and Yuji Imaizumi*
Department of Molecular and Cellular Pharmacology, Faculty of Pharmaceutical
Sciences, Nagoya City University,
3-1 Tanabedori, Mizuhoku, Nagoya 467-8603, Japan
*ﾊTo whom correspondence should be addressed.
Abstract: The single channel current of intermediate conductance
Ca2+-activated K+ channel (IK channel) was measured
in mouse urinary bladder myocytes (MBM), and the molecular basis of the
channel was suggested to be the SK4 subtype by RT-PCR. Among Ca2+-activated
K+ channel subtypes (SK2, SK3, SK4 and BK), the mRNAs of SK4
and BK were predominantly expressed in MBM. IK channel currents recorded
from MBM showed: 38.7ﾊpS slope conductance under symmetrical 140ﾊmM K+
conditions, Ca2+-dependent activation, and blockade by charybdotoxin
and econazole. These results strongly suggest that SK4 encodes IK channels
in MBM.
Keywords: Intermediate conductance Ca2+-activated K+
(IK) channel, SK4, Bladder smooth muscle
Copyrightｩ The Japanese Pharmacological Society 2000
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