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rdf:type |
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lifeskim:mentions |
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pubmed:issue |
2
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pubmed:dateCreated |
1993-12-28
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pubmed:abstractText |
1. Effects of cyclopiazonic acid (CPA), a specific inhibitor of Ca(2+)-ATPase in endo- and sarcoplasmic reticulum (ER/SR), on contractile responses, cytosolic Ca2+ concentration and spontaneous electrical activity were examined in ileal longitudinal smooth muscle strips. 2. After intracellular stored Ca2+ in intact ileal strips was depleted by application of 25 mM caffeine in Ca(2+)-free solution, Ca(2+)-loading was performed in the absence or presence of 10 microns CPA in a standard solution containing 2.2 mM Ca2+. Subsequent application of caffeine in Ca(2+)-free solution induced a phasic contraction which was significantly smaller in the strip pretreated with CPA than that in the control. 3. Spontaneous and 20 mM K(+)-induced contractions in the presence of 1 microM atropine were markedly enhanced by 1-30 microM CPA, whereas that induced by 80 mM K+ was not. The magnitude of repetitive transient elevation of cytosolic Ca2+ concentration ([Ca2+])i) and concomitant phasic contractions were markedly enhanced by CPA. The effects were abolished by 10 microM verapamil and restored by 10 microM Bay K 8644. 4. Application of 10 microM CPA depolarized the cell by about 5 mV, decreased the action potential (AP) afterhyperpolarization and markedly increased the frequency of spontaneous AP. These effects were mimicked by 100 nM charybdotoxin. 5. The rate of decay of [Ca2+]i and tension after the bathing solution was changed from one containing 140 mM K+ and 2.2 mM Ca2+ to one containing 5.9 mM K+ and 0 mM Ca2+ was significantly slowed when 10 microM CPA was added to the latter solution. 6. These results indicate that CPA enhances ileal smooth muscle excitability and increases Ca2+-influx through voltage-dependent Ca2+ channels. The effect may be consistent with the hypothesis that CPA-induced decrease in stored Ca due to Ca-pump inhibition reduces the Ca2+-dependent K+ current and indirectly enhances Ca2+-influx through membrane activity resulting from the increased excitability.Direct evidence for the regulation of Ca2+ channel activity by intracellular Ca storage sites was not obtained in the present study.
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pubmed:commentsCorrections |
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1281502,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1284565,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1309940,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1310236,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1328734,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1330156,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1373909,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1380709,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1386774,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1387024,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1403820,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1531101,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1531138,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1533181,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1534201,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1553257,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1696988,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1709502,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1716053,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1730576,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1834651,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1834695,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1950586,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1953794,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-1965707,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2138778,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2213595,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2213601,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2244912,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2409600,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2420465,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2436483,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2442353,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2509451,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2530215,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2532015,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2544853,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2592951,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2618852,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2663854,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2667516,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2704996,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2794970,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-2964239,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-3125371,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-3219482,
http://linkedlifedata.com/resource/pubmed/commentcorrection/8242231-3821941
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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 |
Oct
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pubmed:issn |
0007-1188
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pubmed:author |
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pubmed:issnType |
Print
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pubmed:volume |
110
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
565-72
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pubmed:dateRevised |
2010-11-18
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pubmed:meshHeading |
pubmed-meshheading:8242231-Animals,
pubmed-meshheading:8242231-Atropine,
pubmed-meshheading:8242231-Caffeine,
pubmed-meshheading:8242231-Calcium,
pubmed-meshheading:8242231-Calcium-Transporting ATPases,
pubmed-meshheading:8242231-Cytosol,
pubmed-meshheading:8242231-Electrophysiology,
pubmed-meshheading:8242231-Guinea Pigs,
pubmed-meshheading:8242231-Ileum,
pubmed-meshheading:8242231-Indoles,
pubmed-meshheading:8242231-Male,
pubmed-meshheading:8242231-Membrane Potentials,
pubmed-meshheading:8242231-Muscle, Smooth,
pubmed-meshheading:8242231-Muscle Contraction,
pubmed-meshheading:8242231-Nerve Fibers,
pubmed-meshheading:8242231-Potassium,
pubmed-meshheading:8242231-Sarcoplasmic Reticulum
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pubmed:year |
1993
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pubmed:articleTitle |
Cyclopiazonic acid, an inhibitor of Ca(2+)-ATPase in sarcoplasmic reticulum, increases excitability in ileal smooth muscle.
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