Linked Life Data

17298845

Source:http://linkedlifedata.com/resource/pubmed/id/17298845

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2007-7-25
pubmed:abstractText
Recent studies have highlighted the role of the sarcoplasmic reticulum (SR) in controlling excitability, Ca2+ signalling and contractility in smooth muscle. Caffeine, an agonist of ryanodine receptors (RyRs) on the SR has been previously shown to effect Ca2+ signalling but its effects on excitability and contractility are not so clear. We have studied the effects of low concentration of caffeine (1 mM) on Ca2+ signalling, action potential and contractility of guinea pig ureteric smooth muscle. Caffeine produced reversible inhibition of the action potentials, Ca2+ transients and phasic contractions evoked by electrical stimulation. It had no effect on the inward Ca2+ current or Ca2+ transient but increased the amplitude and the frequency of spontaneous transient outward currents (STOCs) in voltage clamped ureteric myocytes, suggesting Ca2+-activated K+ channels (BK) are affected by it. In isolated cells and cells in situ caffeine produced an increase in the frequency and the amplitude of Ca2+ sparks as well the number of spark discharging sites per cell. Inhibition of Ca2+ sparks by ryanodine (50 microM) or SR Ca2+-ATPase (SERCA) cyclopiazonic acid (CPA, 20 microM) or BKCa channels by iberiotoxin (200 nM) or TEA (1 mM), fully reversed the inhibitory effect of caffeine on Ca2+ transients and force evoked by electrical field stimulation (EFS). These data suggest that the inhibitory effect of caffeine on the action potential, Ca2+ transients and force in ureteric smooth muscle is caused by activation of Ca2+ sparks/STOCs coupling mechanism.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0143-4160
pubmed:author
pubmed:issnType
Print
pubmed:volume
42
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
303-11
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Evidence that a Ca2+ sparks/STOCs coupling mechanism is responsible for the inhibitory effect of caffeine on electro-mechanical coupling in guinea pig ureteric smooth muscle.
pubmed:affiliation
The Physiological Laboratory, University of Liverpool, Crown Street, Liverpool L69 3BX, UK.
pubmed:publicationType
Journal Article