Linked Life Data

149666

Source:http://linkedlifedata.com/resource/pubmed/id/149666

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:dateCreated
1978-9-15
pubmed:abstractText
In striated muscle the transition from the active to the resting state requires a reduction in the cytosolic concentration of ionized calcium (Ca2+), achieved by a rapid sequestration into the sarcoplasmic reticulum and the return of some Ca2+ to the extracellular phase. Morphologically the sarcoplasmic reticulum (SR) is heterogeneous. Specialized regions occur whenever the limiting membranes of the SR approach those of the plasmalemma. These specializations include a narrowed lumen, relative to that found in non-specialized parts of the SR, the presence of electron-dense 'feet' extending into the junctional gap separating the facing membranes of the plasmalemma and the SR, and the occurrence of intraluminal densities. These specializations can assume a variety of configurations, some of which appear to be species specific. The accumulation of Ca2+ by the SR, is a rapid process and the required energy is derived from the hydrolysis of ATP via a Ca2+-activated ATPase in the limiting membranes of the SR. Impaired relaxation in heart muscle can result either from an inadequate supply of ATP, Ca2+-overload, failure of the Ca2+-activated ATPase enzyme, leakage of Ca2+ from the SR, or the failure of the cell to return Ca2+ back into the extracellular phase. Evidence will be presented to show that the rise in resting tension that is caused by an inadequate supply of oxygen involves a mobilization of Ca2+ from the internal stores, and insufficient ATP to drive the ATPase enzyme in the SR, rather than a malfunction of the enzyme. Likewise ouabain-induced contractures have been found to be associated with diminished tissue stores of ATP, the rise in tissue Ca2+ occurring as a late phenomenon.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0301-4711
pubmed:author
pubmed:issnType
Print
pubmed:volume
7 Suppl
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
35-50
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed:year
1978
pubmed:articleTitle
Relaxation in heart muscle: some morphological and biochemical considerations.
pubmed:publicationType
Journal Article