Linked Life Data

18007024

Source:http://linkedlifedata.com/resource/pubmed/id/18007024

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
2008-2-1
pubmed:abstractText
Stimulation of nitric oxide (NO) release from the coronary endothelium facilitates myocardial relaxation via a cGMP-dependent reduction in myofilament Ca2+ sensitivity. Recent evidence suggests that NO released by a neuronal NO synthase (nNOS) in the myocardium can also hasten left ventricular relaxation; however, the mechanism underlying these findings is uncertain. Here we show that both relaxation (TR50) and the rate of [Ca2+]i transient decay (tau) are significantly prolonged in field-stimulated or voltage-clamped left ventricular myocytes from nNOS-/- mice and in wild-type myocytes (nNOS+/+) after acute nNOS inhibition. Disabling the sarcoplasmic reticulum abolished the differences in TR50 and tau, suggesting that impaired sarcoplasmic reticulum Ca2+ reuptake may account for the slower relaxation in nNOS-/- mice. In line with these findings, disruption of nNOS (but not of endothelial NOS) decreased phospholamban phosphorylation (P-Ser16 PLN), whereas nNOS inhibition had no effect on TR50 or tau in PLN-/- myocytes. Inhibition of cGMP signaling had no effect on relaxation in either group whereas protein kinase A inhibition abolished the difference in relaxation and PLN phosphorylation by decreasing P-Ser16 PLN and prolonging TR50 in nNOS+/+ myocytes. Conversely, inhibition of type 1 or 2A protein phosphatases shortened TR50 and increased P-Ser16 PLN in nNOS-/- but not in nNOS+/+ myocytes, in agreement with data showing increased protein phosphatase activity in nNOS-/- hearts. Taken together, our findings identify a novel mechanism by which myocardial nNOS promotes left ventricular relaxation by regulating the protein kinase A-mediated phosphorylation of PLN and the rate of sarcoplasmic reticulum Ca2+ reuptake via a cGMP-independent effect on protein phosphatase activity.
pubmed:commentsCorrections
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
1524-4571
pubmed:author
pubmed:issnType
Electronic
pubmed:day
1
pubmed:volume
102
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
242-9
pubmed:meshHeading
pubmed:year
2008
pubmed:articleTitle
Reduced phospholamban phosphorylation is associated with impaired relaxation in left ventricular myocytes from neuronal NO synthase-deficient mice.
pubmed:affiliation
Department of Cardiovascular Medicine, University of Oxford, John Radcliffe Hospital, United Kingdom.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't