Linked Life Data

8889662

Source:http://linkedlifedata.com/resource/pubmed/id/8889662

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1997-2-3
pubmed:abstractText
We studied the subcellular mechanisms of the negative force-frequency relationship in rat myocardium by measuring 1) intracellular Ca2+ transients by indo-1 fluorometry and 2) intracellular pH (pHi) and phosphate compounds with 31P-nuclear magnetic resonance (NMR). The data were compared with those from guinea pig hearts, which show a positive force-frequency relationship. By increasing the pacing rate from 3 Hz to 5 Hz, the peak positive first derivative of left ventricular pressure (LVdP/dt) in rat heart decreased by 10 +/- 1% (n = 6). In contrast to this negative inotropic response, simultaneously measured peak Ca2+ transients increased by 6 +/- 1%. Guinea pig heart (n = 6) showed an increase in peak positive LVdP/dt (33 +/- 1%) which was associated with an increase in peak Ca2+ transients (8 +/- 1%). Under equivalent experimental conditions in an NMR spectrometer, this increase in the pacing rate did not affect intracellular levels of phosphate compounds in either rat (n = 6) or guinea pig heart (n = 6). In contrast, pHi showed a decrease of 0.031 +/- 0.006 pH units in rat heart, while no changes were observed in guinea pig heart. These results suggest that in physiological rat myocardium, pHi is susceptible to changes in the stimulus frequency and may affect the Ca(2+)-responsiveness of contractile proteins, which results in the negative force-frequency relationship.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0047-1828
pubmed:author
pubmed:issnType
Print
pubmed:volume
60
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
593-603
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Mechanism of the negative force-frequency relationship in physiologically intact rat ventricular myocardium--studies by intracellular Ca2+ monitor with indo-1 and by 31P-nuclear magnetic resonance spectroscopy.
pubmed:affiliation
Department of Internal Medicine, Kyoto University Faculty of Medicine, Japan.
pubmed:publicationType
Journal Article, In Vitro