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[Analysis by two-dimensional electrophoresis of the cause of myocardial dysfunction in aging rat hearts]
H Minami1, T Nagane, H Sugawara
1First Department of Internal Medicine, Asahikawa Medical College.
Insights
Aging hearts show reduced contractile proteins, including myosin heavy chain and actin, leading to decreased myocardial contractility. This study highlights key molecular changes in the aging rat heart.
Area of Science:
- Cardiovascular Biology
- Molecular Cardiology
- Gerontology
Context:
- Cardiac function is significantly impacted by age-related diseases like atherosclerosis and diabetes.
- While hemodynamic and histopathological changes in aging hearts are documented, alterations in structural proteins remain understudied.
Purpose:
- To investigate age-related changes in contractile proteins within the left ventricles of aging rats.
- To identify specific protein alterations contributing to impaired cardiac function in senescence.
Summary:
- Two-dimensional electrophoresis revealed no significant differences in structural proteins between 6-week and 12-week-old rats.
- In 125-week-old rats, the content of key contractile proteins, including myosin heavy chain, myosin light chain 2, actin, and troponin-I, was significantly decreased compared to 12-week-old rats.
- A reduction in myosin heavy chain, crucial for converting chemical to mechanical energy, directly correlates with diminished myocardial contractility.
Impact:
- The findings identify decreased contractile protein content as a critical molecular change in the aging rat heart.
- This molecular shift contributes to impaired myocardial contractility and relaxation, alongside increased interstitial fibrosis and reduced calcium uptake.
- Provides insights into the molecular mechanisms underlying age-related cardiac dysfunction, informing potential therapeutic targets.
Abstract:
The severity and frequency of atherosclerosis, diabetes, and ischemic heart disease, which affect cardiac function, increase with aging. Although there are many reports about hemodynamic and histopathological studies about aging hearts, there are very few studies on changes in structural proteins in aging hearts. We investigated the contractile proteins of the left ventricles in rats aged 6, 12 and 125 weeks using two-dimensional electrophoresis. There were no difference in structural proteins in heart between 6-week and 12-week-old rats. The contents of myosin heavy chain, myosin light chain 2, actin, troponin-I in 125-week-old rats decreased compared with those of 12-week-old rats. Myosin heavy chain, which is one component of myosin, interacts with actin and changes chemical energy to mechanical energy. Therefore its decrease leads to a decline in myocardial contractility. These results seem to indicate one of the most important changes in the aging rat heart, as well as impairment in relaxation by the increase of interstitial fibrosis and decline of Ca uptake by sarcoplasmic reticulum.