Linked Life Data

6238628

Source:http://linkedlifedata.com/resource/pubmed/id/6238628

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
1985-1-14
pubmed:abstractText
The contractile system of smooth muscle exhibits distinctive responses to varying Mg2+ concentrations in that maximum adenosine-5'-triphosphatase (ATPase) activity of actomyosin requires relatively high concentrations of Mg2+ and also that tension in skinned smooth muscle fibers can be induced in the absence of Ca2+ by high Mg2+ concentrations. We have examined the effects of MgCl2 on actomyosin ATPase activity and on tension development in skinned gizzard fibers and suggest that the MgCl2-induced changes may be correlated to shifts in myosin conformation. At low concentrations of free Mg2+ (less than or equal to 1 mM) the actin-activated ATPase activity of phosphorylated turkey gizzard myosin is reduced and is increased as the Mg2+ concentration is raised. The increase in Mg2+ (over a range of 1-10 mM added MgCl2) induces the conversion of 10S phosphorylated myosin to the 6S form, and it was found that the proportion of myosin as 10S is inversely related to the level of actin-activated ATPase activity. Activation of the actin-activated ATPase activity also occurs with dephosphorylated myosin but at higher MgCl2 concentrations, between 10 and 40 mM added MgCl2. Viscosity and fluorescence measurements indicate that increasing Mg2+ levels over this concentration range favor the formation of the 6S conformation of dephosphorylated myosin, and it is proposed that the 10S to 6S transition is a prerequisite for the observed activation of ATPase activity. With glycerinated chicken gizzard fibers high MgCl2 concentrations (6-20 mM) promote tension in the absence of Ca2+.(ABSTRACT TRUNCATED AT 250 WORDS)
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Oct
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
9
pubmed:volume
23
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
5062-8
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1984
pubmed:articleTitle
Effects of magnesium chloride on smooth muscle actomyosin adenosine-5'-triphosphatase activity, myosin conformation, and tension development in glycerinated smooth muscle fibers.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't