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rdf:type |
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lifeskim:mentions |
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pubmed:dateCreated |
1990-2-22
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pubmed:abstractText |
1. The effects of caffeine (0.2-20 mmol l-1) have been examined on calcium transients (measured with aequorin) and isometric force in intact bundles of fibres from soleus (slow-twitch) and extensor digitorum longus (EDL; fast-twitch) muscles of the rat. 2. At 25 degrees C, threshold caffeine concentration for an observable increase in resting [Ca2+]i was 0.2 and 1.0 mmol l-1 for soleus and EDL muscles respectively. Increases in resting force were first detectable at about 0.5 mmol l-1 caffeine for soleus muscles and 5.0 mmol l-1 caffeine for EDL muscles and occurred in the range 0.2-0.4 mumol l-1 [Ca2+]i for soleus and 0.7-0.9 mumol l-1 for EDL. 3. Caffeine potentiated the twitch responses of soleus and EDL in a dose-related manner. The soleus was more sensitive in this respect, with 50% potentiation occurring at 1 mmol l-1 caffeine compared with 3.5 mmol l-1 for the EDL. Concentrations of caffeine below 2 mmol l-1 potentiated Ca2+ transients associated with twitches in both soleus and EDL muscles with no apparent change in the decay rate constant. 4. High concentrations of caffeine (greater than 2 mmol l-1) further potentiated peak Ca2+ in the EDL but depressed it in the soleus. The rate of decay of the Ca2+ transient in high caffeine was significantly prolonged in the soleus but remained unaffected in the EDL. 5. The phosphodiesterase inhibitor, 3-isobutyl-1-methylxanthine (IBMX) had little effect on force or [Ca2+]i at concentrations known to significantly increase intracellular cyclic AMP levels. 6. The Ca2+ transient during fused tetani was characterized by an initial peak, a decline to a plateau level and sometimes a gradual rise towards the end of the stimulus train. Peak [Ca2+]i during normal tetani ranged between 1.1 and 2.4 mumol l-1 in the soleus and 1.9 and 4.0 mumol l-1 in the EDL. 7. Caffeine potentiated both force and [Ca2+]i during tetanus. Since the increase of the Ca2+ transient was significantly greater than potentiation of force, it is likely that saturation of myofilaments occurs. The primary effect of caffeine on the Ca2+ transient was an elevation of the plateau phase. 8. Caffeine concentrations below 5 mmol l-1 potentiate twitch and tetanic force in both fast- and slow-twitch mammalian skeletal muscles primarily by increasing both the basal and stimulus-evoked release of Ca2+ from the sarcoplasmic reticulum.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-13605807,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-14080325,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-2581101,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-2938950,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-2963132,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-306438,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-310523,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-3256625,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-3412868,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-3488409,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-3498820,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-3795067,
http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-3875711,
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http://linkedlifedata.com/resource/pubmed/commentcorrection/2607458-7366724
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pubmed:language |
eng
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pubmed:journal |
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pubmed:citationSubset |
IM
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pubmed:chemical |
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pubmed:status |
MEDLINE
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pubmed:month |
Sep
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pubmed:issn |
0022-3751
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
416
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
435-54
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pubmed:dateRevised |
2009-11-18
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pubmed:meshHeading |
pubmed-meshheading:2607458-Action Potentials,
pubmed-meshheading:2607458-Aequorin,
pubmed-meshheading:2607458-Animals,
pubmed-meshheading:2607458-Caffeine,
pubmed-meshheading:2607458-Calcium,
pubmed-meshheading:2607458-Dose-Response Relationship, Drug,
pubmed-meshheading:2607458-Isometric Contraction,
pubmed-meshheading:2607458-Male,
pubmed-meshheading:2607458-Membrane Potentials,
pubmed-meshheading:2607458-Muscles,
pubmed-meshheading:2607458-Rats,
pubmed-meshheading:2607458-Rats, Inbred Strains
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pubmed:year |
1989
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pubmed:articleTitle |
Actions of caffeine on fast- and slow-twitch muscles of the rat.
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pubmed:affiliation |
School of Physiology and Pharmacology, University of NSW, Kensington, Sydney, Australia.
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pubmed:publicationType |
Journal Article
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