Left ventricular function and remodeling after myocardial infarction in aging rats

Thomas E. Raya, Mohamed Gaballa, Peter Anderson, Steven Goldman

Research output: Contribution to journalArticle

64 Scopus citations

Abstract

Adaptations of the aging left ventricle (LV) to hemodynamic overload are functionally and structurally distinct from those of the young organism. This study describes the influence of aging on LV hemodynamics and remodeling late after myocardial infarction (MI) in Fischer 344 Brown Norway rats. In sham rats at 23 mo, LV weight, myocyte cross-sectional area (CSA), and myocardial fibrosis were increased, whereas LV dP/dt, LV relaxation, and maximal LV systolic function declined with respect to younger rats (7, 12, and 18 mo of age). Isometric myocardial function was evaluated in papillary muscles of 12- and 23-mo-old sham rats. Myocardial systolic function was decreased in older rats. To determine how aging affects LV function and remodeling after MI, rats were infarcted at 7 and 18 mo of age and were studied 5 mo later. Infarct size was similar in each group. Right ventricular weight, LV end- diastolic pressure, and volume index were increased, whereas LV dP/dt, peak cardiac index, and peak developed LV pressure declined after MI. However, there were no significant differences between young and older rats in any variable of LV systolic function or remodeling after MI. Myocyte CSA increased in younger rats after MI but was unchanged in 23-mo-old rats. After MI, myocardial fibrosis was significantly increased from baseline only in younger rats. The negative interaction of aging and MI on myocyte hypertrophy and fibrosis was highly significant. The findings indicate that baseline LV and myocardial function decline with age. In the aging rat after MI, despite limited compensatory hypertrophy and more advanced baseline myocardial fibrosis, the long-term functional and structural adaptations to MI are similar to those of the mature adult heart.

Original languageEnglish (US)
Pages (from-to)H2652-H2658
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume273
Issue number6 42-6
StatePublished - Dec 1 1997
Externally publishedYes

Keywords

  • Fibrosis
  • Hypertrophy
  • Myocardial function

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine
  • Physiology (medical)

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