Linked Life Data

8789414

Source:http://linkedlifedata.com/resource/pubmed/id/8789414

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
11
pubmed:dateCreated
1997-1-17
pubmed:abstractText
Effects of Ca2+ channel blockers, such as nifedipine, nimodipine, gallopamil, verapamil, diltiazem, loperamide, Mn2+ and Ni2+, and papaverine, on contractile responses to K+ depolarization were evaluated in longitudinal muscles of taenia coli isolated from guinea-pig. Depolarization with high K+ solution (K+, 40 mM) produced a biphasic (phasic and tonic) contraction, which was inhibited by the above blockers in a concentration-dependent manner. Ratios of IC50 for the phasic contraction to IC50 for the tonic contraction of nimodipine, verapamil, gallopamil, nifedipine, loperamide, diltiazem, papaverine, Ni2+, and Mn2+ were 516.1, 73.7, 22.0, 6.4, 5.3, 4.9, 1.2, 0.7, and 0.1, respectively, indicating that nimodipine suppressed the tonic contraction more effectively than the phasic contraction. In a fluorescence study with fura 2, K+ depolarization elicited an increase in intracellular free Ca2+, [Ca2+]i, which was coupled with the phasic and tonic contraction. The increases in [Ca2+]i coupled with both types of the contraction were abolished by exposure to Ca(2+)-free solution. In addition, the increase of [Ca2+]i coupled with the phasic contraction was abolished by nifedipine, 10(-7) M, but not by nimodipine, 10(-7) M, whereas the increase with the tonic contraction was suppressed by both nifedipine and nimodipine. These findings suggest that the phasic and tonic contractions evoked by K+ depolarization are due to increases in [Ca2+]i via activation of respective nimodipine-resistant and nimodipine-sensitive Ca2+ channels in the longitudinal muscles of the taenia coli. Accordingly, nimodipine, but not nifedipine, appears to be a useful tool for distinguishing between the phasic and tonic contractions.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Nov
pubmed:issn
0008-4212
pubmed:author
pubmed:issnType
Print
pubmed:volume
73
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1600-4
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1995
pubmed:articleTitle
Discrimination by nimodipine, but not by nifedipine, between phasic and tonic contractions of guinea-pig taenia coli induced by K+ depolarization.
pubmed:affiliation
Research Laboratory of Biodynamics, Fukuoka University, Japan.
pubmed:publicationType
Journal Article, Comparative Study, In Vitro