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Load induction of cardiac hypertrophy.
1Department of Medicine, Veterans Administration Medical Center, Charleston, SC.
Journal of Molecular and Cellular Cardiology
|December 1, 1989
Summary
Cardiac load directly regulates heart muscle size. Increased load causes hypertrophy (growth), while decreased load leads to atrophy (shrinkage), independent of external factors. This process involves cell membrane changes and sodium ion influx.
Area of Science:
- Cardiology
- Cell Biology
- Physiology
Background:
- Cardiac loading influences myocardial mass in vivo.
- Changes in cardiac load are reversible and independent of neural or humoral factors.
Purpose of the Study:
- Demonstrate load-induced cardiac changes in isolated cardiocytes.
- Elucidate the mechanism of load transduction into cardiac mass changes in papillary muscles.
Main Methods:
- Cultured isolated adult cardiocytes (adherent and suspension).
- Studied quiescent and contracting isolated papillary muscles.
- Measured nuclear RNA and protein synthesis in response to mechanical load.
Main Results:
- Unloaded cardiocytes in suspension ceased RNA synthesis, mimicking atrophy.
- Loaded, stretched cardiocytes initiated synthetic activity, mimicking hypertrophy.
- Papillary muscles showed load-dependent protein synthesis linked to muscle tension.
Conclusions:
- Cardiac load is an independent regulator of adult cardiac growth.
- Sarcolemmal deformation and sodium influx may mediate load-induced cardiac growth.