Cytochalasin D Inhibits Smooth Muscle Contraction by Directly Inhibiting Contractile Apparatus.
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- SAITO Shin-ya
- Department of Veterinary Pharmacology, Graduate School of Agriculture
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- HORI Masatoshi
- Department of Veterinary Pharmacology, Graduate School of Agriculture
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- OZAKI Hiroshi
- Life Sciences, The University of Tokyo
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- KARAKI Hideaki
- Life Sciences, The University of Tokyo
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Abstract
We investigated the mode of relaxant effects of cytochalasin D, a capping agent of actin filaments, on contractile responses in the rat aorta and chicken gizzard smooth muscles.Cytochalasin D inhibited the contraction induced by high K+ or noradrenaline (10nM-1μM) without changing cytosolic Ca2+ level ([Ca2+] i) in the rat aorta. In the absence of external Ca2+, 12-deoxyphorbol 13-isobutylate (DPB) (1μM) induced sustained contraction without increasing in [Ca2+] i and cytochalasin D also inhibited this contraction. In the permeabilized chicken gizzard smooth muscle, cytochalasin D inhibited the Ca2+ (1-10μM)-induced contraction. Cytochalasin D also inhibited the Ca2+-independent contraction in the muscle which had been thiophosphorylated by ATPγS. Cytochalasin D decreased the velocity of superprecipitation in the chicken gizzard native actomyosin (myosin B) affecting neither the level of MLC phosphorylation nor Mg2+-ATPase activity. These results suggest that cytochalasin D inhibits smooth muscle contractions without any effect on the Ca2+-dependent MLC phosphorylation or subsequent activation of myosin ATPase activity. Based on these evidences, it is concluded that cytochalasin D may inhibit smooth muscle contraction possiblly through uncoupling of the force generation from the activated actomyosin Mg2+-ATPase.
Journal
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- Journal of Smooth Muscle Research
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Journal of Smooth Muscle Research 32 (2), 51-60, 1996
Japan Society of Smooth Muscle Research
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Details 詳細情報について
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- CRID
- 1390282680032816384
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- NII Article ID
- 130002034988
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- COI
- 1:CAS:528:DyaK28Xls1GmsLg%3D
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- ISSN
- 18848796
- 09168737
- http://id.crossref.org/issn/09168737
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- PubMed
- 8845566
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- Text Lang
- en
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- Data Source
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- JaLC
- Crossref
- PubMed
- CiNii Articles
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- Abstract License Flag
- Disallowed