| Electromechanical effects of okadaic acid isolated from black sponge in guinea-pig ventricular muscles. | |
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MedLine Citation:
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PMID: 3795107 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Okadaic acid is a monocarboxylic acid with a unique molecular structure of C44H66O13. Okadaic acid, at concentrations above 10(-5) M, caused a dose-dependent increase of contractile force in guinea-pig isolated ventricular muscles. The increase of contractile force by okadaic acid (1-4 X 10(-5) M) was accompanied by a prolongation of action potential duration (a.p.d.), while a.p.d. was shortened by okadaic acid at above 10(-4) M. The okadaic-acid-induced changes in contractile force and a.p.d. were abolished by pre-treatment with verapamil (2 X 10(-6 M) or nifedipine (10(-6) M). In a low-Ca2+ medium (0.12 mM), the contractile response to okadaic acid (4 X 10(-5) M) was inhibited, whereas the a.p.d. was more prolonged by the drug than in a control medium (containing 1.2 mM-Ca2+). In a low-Na+ (70 mM) medium or in a low-Na+ (70 mM) and low-Ca2+ (0.12 mM) medium both the contractile force and a.p.d. were unaffected by okadaic acid (4 X 10(-5) M). The positive inotropic effect of okadaic acid (4 X 10(-5) M) was not inhibited by treatment with tetrodotoxin (TTX, 2 X 10(-6) M) or with ryanodine (2 X 10(-6) M). In voltage-clamp experiments using a single sucrose-gap technique, okadaic acid (4 X 10(-5) M), caused a significant increase of slow inward current, while it did not affect the net outward current. These findings suggest that okadaic acid has a positive inotropic effect on the heart, probably due to the enhancement of slow Ca2+ and/or Na+ inward current through the cell membrane. |
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Authors:
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I Kodama; N Kondo; S Shibata |
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Publication Detail:
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Type: In Vitro; Journal Article |
Journal Detail:
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Title: The Journal of physiology Volume: 378 ISSN: 0022-3751 ISO Abbreviation: J. Physiol. (Lond.) Publication Date: 1986 Sep |
Date Detail:
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Created Date: 1987-02-19 Completed Date: 1987-02-19 Revised Date: 2009-11-18 |
Medline Journal Info:
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Nlm Unique ID: 0266262 Medline TA: J Physiol Country: ENGLAND |
Other Details:
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Languages: eng Pagination: 359-73 Citation Subset: IM |
Export Citation:
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| MeSH Terms | |
Descriptor/Qualifier:
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Action Potentials
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drug effects Animals Calcium / pharmacology Calcium Channel Blockers / pharmacology Ethers, Cyclic / pharmacology* Guinea Pigs Muscle Contraction / drug effects* Muscles / physiology* Okadaic Acid Papillary Muscles / physiology Porifera / metabolism Sodium / pharmacology Tetrodotoxin / pharmacology |
| Chemical | |
Reg. No./Substance:
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0/Calcium Channel Blockers; 0/Ethers, Cyclic; 4368-28-9/Tetrodotoxin; 7440-23-5/Sodium; 7440-70-2/Calcium; 78111-17-8/Okadaic Acid |
| Comments/Corrections | |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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