Linked Life Data

8118962

Source:http://linkedlifedata.com/resource/pubmed/id/8118962

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1994-4-6
pubmed:abstractText
In vitro biochemical experiments have suggested that stimulation of beta-adrenergic receptor may increase the rate of crossbridge cycling in mammalian myocardium, but recent attempts to demonstrate a mechanical correlate have yielded conflicting results. To investigate this issue, we measured the effect of isoproterenol (ISO) and cAMP-dependent protein kinase (PKA) on unloaded shortening velocity (Vo). Vo is thought to be determined by the rate-limiting step of the crossbridge cycle, ie, the rate of crossbridge detachment from actin, and is therefore an index of the cycling rate. Single rat ventricular myocytes were enzymatically isolated, incubated in Ringer's solution without (control) or with 0.1 mumol/L ISO, and then rapidly skinned. Some control cells were subsequently treated with 3 micrograms/mL PKA for 40 minutes. Vo was then measured during maximal activation (pCa 4.5) in control, ISO-treated, and PKA-treated cells using the slack-test method. To test the efficacy of the agonist treatments, Ca2+ sensitivity of isometric tension was also assessed for each treatment by determining the [Ca2+] required for half-maximal tension (ie, pCa50). Both ISO and PKA treatment reduced the Ca2+ sensitivity of isometric tension compared with same-day control cells, in agreement with previous studies in intact and in skinned preparations. Vo was increased 38% by ISO treatment and 41% by PKA treatment compared with same-day control cells. 32P autoradiography showed that troponin I and C protein were the principal proteins phosphorylated by PKA treatment. We conclude that beta-adrenergic stimulation increases the rate of crossbridge release from actin, by a mechanism that most likely involves the phosphorylation of troponin I and/or C protein by PKA.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Mar
pubmed:issn
0009-7330
pubmed:author
pubmed:issnType
Print
pubmed:volume
74
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
542-9
pubmed:dateRevised
2007-11-15
pubmed:meshHeading
pubmed:year
1994
pubmed:articleTitle
Beta-adrenergic receptor stimulation increases unloaded shortening velocity of skinned single ventricular myocytes from rats.
pubmed:affiliation
Department of Physiology, School of Medicine, University of Wisconsin, Madison.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, Non-U.S. Gov't