Effect of Phorbol Esters on Cytosolic Ca2+ Level, Myosin Phosphorylation and Muscle Tension in High K+-Stimulated Bovine Tracheal Smooth Muscle.
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- Tajimi Masaomi
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo Bayer Yakuhin, Ltd., Institute of Allergy, Research Center Kyoto
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- Hori Masatoshi
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo
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- Ozaki Hiroshi
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo
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- Karaki Hideaki
- Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo
Bibliographic Information
- Other Title
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- Effect of Phorbol Esters on Cytosolic C
- Effect of phorbol esters on cytosolic Ca2+ level, myosin phosphorylation and muscle tension in high K(+)‐stimulated bovine tracheal smooth muscle
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Abstract
To determine the role of protein kinase C (PKC)in bovine tracheal smooth muscle contractility, we examined the effects of phorbol esters on cytosolic Ca2+ level ([Ca2+]i), myosin light chain (MLC) phosphorylation and contractile force in intact muscle and contraction in a permeabilized preparation. In intact muscle, 12-deoxyphorbol 13-isobutyrate (DPB, 1 μM)increased the force without changing [Ca2+]i. High K+ (72.7 mM) induced sustained contraction with sustained increase in [Ca2+]i. In the muscle stimulated by high K+, 50 nM DPB increased the contractile force without changing [Ca2+]i, and 1 μM DPB increased the contractile force with decreasing [Ca2+]i. Thus DPB shifted the [Ca2+]i/force relationship for high K+ to the lower [Ca2+]i in a concentration-dependent manner. In permeabilized muscle, DPB did not induce contraction in the absence of Ca2+ (<<0 nM), but shifted the Ca2+/force relationship to the lower Ca2+ levels. In the muscle stimulated with high K+, DPB (50 nM and 1 μM)increased MLC phosphorylation and force without changing the MLC phosphorylation/force relationship. DPB (1 μM) increased PKC activity estimated by the translocation from the cytoplasm to the membrane. These results suggest that DPB increases the Ca2+ sensitivity of MLC phosphorylation via the activation of PKC. Furthermore, DPB at higher concentration has an inhibitory effect on stimulated [Ca2+]i.
Journal
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- The Japanese Journal of Pharmacology
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The Japanese Journal of Pharmacology 74 (2), 195-201, 1997
The Japanese Pharmacological Society
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Keywords
Details 詳細情報について
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- CRID
- 1390282679262998912
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- NII Article ID
- 10008678988
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- NII Book ID
- AA00691188
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- COI
- 1:CAS:528:DyaK2sXktVOgtr4%3D
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- ISSN
- 13473506
- 00215198
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- NDL BIB ID
- 4260349
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- PubMed
- 9243328
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- Text Lang
- en
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- Data Source
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- JaLC
- NDL
- Crossref
- PubMed
- CiNii Articles
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- Abstract License Flag
- Disallowed