Article
Coronary vessels and cardiac myocytes of middle-aged rats demonstrate regional sex-specific adaptation in response to postmyocardial infarction remodeling
Biology of Sex Differences
(2014)
Abstract
Background: An increasing body of evidence indicates that left ventricular (LV) remodeling, especially the degree
of reactive myocardial hypertrophy after myocardial infarction (MI), differs in males and females. Surprisingly, to date,the sex-specific post-MI alterations of the coronary vasculature remain undetermined. Therefore, we tested thehypothesis that adaptive coronary arteriolar and capillary modifications occurring in response to reactive myocytehypertrophy differ between middle-aged male and female post-MI rats.
Methods: A large MI was induced in 12-month-old male (M-MI) and female (F-MI) Sprague–Dawley rats by ligation of
the left coronary artery. Four weeks after surgery, rats with transmural infarctions, greater than 50% of the LV free wall(FW), were evaluated. Sham-operated male (M-Sham) and female (F-Sham) rats served as an age-matched controls.
Results: F-MI and M-MI rats had similar sized infarcts (61.3% ± 3.9% vs. 61.5% ± 1.2%) and scale of LV remodeling,
as indicated analogous remodeling indices (1.41 ± 0.11 vs. 1.39 ± 0.09). The degree of reactive post-MI myocardialhypertrophy was adequate to normalize LV weight-to-body weight ratio in both sexes; however, the F-MI rats, incontrast to males, showed no myocyte enlargement in the LVFW epimyocardium. At the same time, a greater than50% expansion of myocyte area in the male epimyocardium and in the female endomyocardium was accompanied
by a 23% (P < 0.05) increase in capillary-to-myocyte ratio, indicative of adaptive angiogenesis. Based on arteriolar length
density in post-MI hearts, the resistance vessels grew in the male LVFW as well as the septum by 24% and 29%,respectively. In contrast, in females, a significant (30%) expansion of arteriolar bed was limited only to the LVFW.Moreover, in F-MI rats, the enlargement of the arteriolar bed occurred predominantly in the vessels with diameters <30 μm, whereas in M-MI rats, a substantial (two- to threefold) increase in the density of larger arterioles (30 to 50 μm in diameter) was also documented.
Conclusion: Our data reveal that while both sexes have a relatively similar pattern of global LV remodeling and
adaptive angiogenesis in response to a large MI, male and female middle-aged rats differ markedly in the regional scaleof reactive cardiac myocyte hypertrophy and adaptive arteriogenesis.
Keywords
- Sex-related differences,
- Myocardial infarction,
- Left ventricular remodeling,
- Myocardial fibrosis,
- Cardiac
Disciplines
Publication Date
January 1, 2014
DOI
https://doi.org/10.1186/2042-6410-5-1
Citation Information
Eduard I Dedkov, Kunal Oak, Lance P Christensen and Robert J Tomanek. "Coronary vessels and cardiac myocytes of middle-aged rats demonstrate regional sex-specific adaptation in response to postmyocardial infarction remodeling" Biology of Sex Differences Vol. 5 Iss. 1 (2014) p. 1 Available at: http://works.bepress.com/edward-dedkov/6/