Linked Life Data

16971497

Source:http://linkedlifedata.com/resource/pubmed/id/16971497

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
1
pubmed:dateCreated
2007-1-12
pubmed:abstractText
To clarify whether activity of the ryanodine receptor type 2 (RyR2) is reduced in the sarcoplasmic reticulum (SR) of cardiac muscle, as is the case with the ryanodine receptor type 1 (RyR1), Ca(2+)-dependent [(3)H]ryanodine binding, a biochemical measure of Ca(2+)-induced Ca(2+) release (CICR), was determined using SR vesicle fractions isolated from rabbit and rat cardiac muscles. In the absence of an adenine nucleotide or caffeine, the rat SR showed a complicated Ca(2+) dependence, instead of the well-documented biphasic dependence of the rabbit SR. In the rat SR, [(3)H]ryanodine binding initially increased as [Ca(2+)] increased, with a plateau in the range of 10-100 microM Ca(2+), and thereafter further increased to an apparent peak around 1 mM Ca(2+), followed by a decrease. In the presence of these modulators, this complicated dependence prevailed, irrespective of the source. Addition of 0.3-1 mM Mg(2+) unexpectedly increased the binding two- to threefold and enhanced the affinity for [(3)H]ryanodine at 10-100 microM Ca(2+), resulting in the well-known biphasic dependence. In other words, the partial suppression of RyR2 is relieved by Mg(2+). Ca(2+) could be a substitute for Mg(2+). Mg(2+) also amplifies the responses of RyR2 to inhibitory and stimulatory modulators. This stimulating effect of Mg(2+) on RyR2 is entirely new, and is referred to as the third effect, in addition to the well-known dual inhibitory effects. This effect is critical to describe the role of RyR2 in excitation-contraction coupling of cardiac muscle, in view of the intracellular Mg(2+) concentration.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0363-6143
pubmed:author
pubmed:issnType
Print
pubmed:volume
292
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
C535-44
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Mg2+ activates the ryanodine receptor type 2 (RyR2) at intermediate Ca2+ concentrations.
pubmed:affiliation
Department of Pharmacology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan. chugun@med.juntendo.ac.jp
pubmed:publicationType
Journal Article