Jpn. J. Pharmacol. 84 (1), 97-100 (2000)

SK4 Encodes Intermediate Conductance Ca2+-Activated K+ Channels in Mouse Urinary Bladder Smooth Muscle Cells

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
*╩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╩pS slope conductance under symmetrical 140╩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

Copyrightę The Japanese Pharmacological Society 2000

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