Linked Life Data

9140804

Source:http://linkedlifedata.com/resource/pubmed/id/9140804

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
2
pubmed:dateCreated
1997-7-8
pubmed:abstractText
A decline in contractility in myocytes from ageing guinea-pig hearts was demonstrated, which is more pronounced for maximum beta-adrenoceptor-stimulated activity than contraction in high Ca2+. In this study the role of the inhibitory G-proteins (Gi) in this process was investigated. Comparisons were made between young (Y, < 400 g, < 4 weeks), adult (A. > 600 g, > 8 weeks) and senescent guinea pigs (S, 58-65 weeks, 1136 +/- 30 g). Gi alpha activity, detected by pertussis toxin-catalysed ADP ribosylation, was significantly increased in senescent compared to young animals, but immunodetectable levels of Gi alpha were unchanged, beta-adrenoceptor number was decreased by 27% in senescent compared with young animals (P < 0.002). Pertussis toxin treatment increased the maximum response to isoproterenol in contacting myocytes so that there was no longer any significant decline with age. Maximum contraction amplitudes (sarcomere length change, micron) with isoproterenol before pertussis toxin were 0.144 +/- 0.011 (Y, n = 22 animals), 0.104 +/- 0.009 (A. 18) and 0.098 +/- 0.009 (S. 14), P < 0.01 by analysis of variance (ANOVA). Following toxin treatment amplitudes were 0.140 +/- 0.012 (Y. 12), 0.117 +/- 0.010 (A. 10) and 0.117 +/- 0.018 (S. 8), P = N.S. Pertussis toxin treatment also reversed the effects of ageing on contraction and relaxation velocity in isoproterenol. In contrast, the effect of age on contraction amplitude or velocity in maximum Ca2+ was more pronounced after toxin treatment. The EC50 value for isoproterenol increased with age: pertussis treatment decreased the EC50 in each group, but the effect was especially pronounced for senescent animals. There was no significant difference in the concentration-response curves for the negative inotropic effect of adenosine (in the presence of isoprotenerol) between the three age groups before toxin treatment. All effects of adenosine were abolished after pertussis exposure. We conclude that increased Gi alpha activity is likely to contribute to the decreased response to isoproterenol, but not to high Ca2+, in myocytes from ageing guinea-pigs.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Feb
pubmed:issn
0022-2828
pubmed:author
pubmed:issnType
Print
pubmed:volume
29
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
439-48
pubmed:dateRevised
2009-11-19
pubmed:meshHeading
pubmed:year
1997
pubmed:articleTitle
The role of Gi-proteins and beta-adrenoceptors in the age-related decline of contraction in guinea-pig ventricular myocytes.
pubmed:affiliation
National Heart and Lung Institute, Imperial College, London, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't