Document Detail

Electromechanical effects of okadaic acid isolated from black sponge in guinea-pig ventricular muscles.
MedLine Citation:
PMID:  3795107     Owner:  NLM     Status:  MEDLINE    
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.
I Kodama; N Kondo; S Shibata
Related Documents :
7469887 - Comparative ototoxicity of chloramphenicol and kanamycin with ethacrynic acid.
11108547 - The uterotonic activity of compounds isolated from the supercritical fluid extract of e...
10511567 - The molecular genetics of red and green color vision in mammals.
17951087 - Atopic cough-like cough hypersensitivity caused by active sensitization with protein fr...
1142007 - Effects of d-, dl-and l-glutamic acid on chicks.
7731677 - N-terminal 130 amino acids of mdm2 are sufficient to inhibit p53-mediated transcription...
Publication Detail:
Type:  In Vitro; Journal Article    
Journal Detail:
Title:  The Journal of physiology     Volume:  378     ISSN:  0022-3751     ISO Abbreviation:  J. Physiol. (Lond.)     Publication Date:  1986 Sep 
Date Detail:
Created Date:  1987-02-19     Completed Date:  1987-02-19     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  0266262     Medline TA:  J Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  359-73     Citation Subset:  IM    
Export Citation:
APA/MLA Format     Download EndNote     Download BibTex
MeSH Terms
Action Potentials / drug effects
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
Reg. No./Substance:
0/Calcium Channel Blockers; 0/Ethers, Cyclic; 4368-28-9/Tetrodotoxin; 7440-23-5/Sodium; 7440-70-2/Calcium; 78111-17-8/Okadaic Acid

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

Previous Document:  Passive transport and binding of lead by human red blood cells.
Next Document:  Rapid resetting of rabbit aortic baroreceptors and reflex heart rate responses by directional change...