Linked Life Data

8187272

Source:http://linkedlifedata.com/resource/pubmed/id/8187272

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
6
pubmed:dateCreated
1994-6-23
pubmed:abstractText
We studied the effect of MgADP on the mechanical interaction of actomyosin in cardiac and skeletal muscles using an in vitro motility assay. The sliding velocities of fluorescently labeled actin filaments on rat cardiac and skeletal myosins were measured at various MgATP and MgADP concentrations. The filament velocity depended on MgATP concentration according to classic Michaelis-Menten kinetics with apparent Michaelis constants (Km) of 43 and 137 mumol/L and maximum velocity of 5.6 and 8.6 microns/s for cardiac and skeletal myosins, respectively. The presence of 2 mmol/L MgADP decreased the filament velocity and shifted the substrate concentration dependence of the velocity toward higher MgATP concentrations, yielding the inhibition constants of 194 and 478 mumol/L for cardiac and skeletal myosins, respectively. The activation energies determined by the temperature dependence of the velocity were 61 and 83 kJ/mol for rat V1 and rabbit cardiac myosins, which were similar to those of the dissociation rate constant of actomyosin-ADP complex reported in a solution study. The inhibition of the velocity by MgADP can be explained by the crossbridge scheme in which MgADP competes with MgATP for the substrate site on myosin molecules. In cardiac myosin, addition of a concentration of MgADP as low as 25 mumol/L significantly inhibited the velocity in the presence of 2 mmol/L MgATP, suggesting that increased intracellular MgADP may reduce the rate of crossbridge detachment, resulting in a decreased ATP consumption and an increased economy of force production under ischemic conditions. The present results support the idea that MgADP may be a physiologically important modulator of contraction in cardiac muscle.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jun
pubmed:issn
0009-7330
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1027-33
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
ADP inhibits the sliding velocity of fluorescent actin filaments on cardiac and skeletal myosins.
pubmed:affiliation
Second Department of Internal Medicine, Faculty of Medicine, University of Tokyo, Japan.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't