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Left ventricle contractile function in trained dogs with cardial hypertrophy
Basic Research in Cardiology
|May 1, 1976
Summary
Chronic exercise induces myocardial hypertrophy in dogs, improving cardiac function. Trained dogs showed better adaptation to pressure overload compared to sedentary controls, highlighting exercise benefits.
Area of Science:
- Cardiovascular Physiology
- Exercise Science
Background:
- Chronic exercise is known to induce cardiac adaptations.
- Myocardial hypertrophy is a common response to exercise training.
Purpose of the Study:
- To investigate the effects of exercise-induced myocardial hypertrophy on cardiac function under various physiological conditions.
- To assess the adaptive mechanisms of the hypertrophied left ventricle in response to acute pressure loading.
Main Methods:
- Eight dogs underwent an 8-week treadmill exercise program, while eight served as controls.
- Hemodynamic and volumetric parameters were measured using left heart catheterization and cineangiography under different conditions (spontaneous, paced heart rate, autonomic blockade, pressure loading).
Main Results:
- Exercise effectively induced myocardial hypertrophy (left ventricular weight/body weight ratio increased significantly).
- No significant intergroup differences in hemodynamic parameters were observed initially.
- Trained dogs showed a less significant increase in left ventricular end-diastolic pressure during acute pressure loading compared to controls.
- Left ventricular end-diastolic volume increased significantly only in control dogs during pressure loading.
Conclusions:
- Exercise-induced myocardial hypertrophy is an adaptive mechanism that benefits intrinsic myocardial contractile function.
- Hypertrophied ventricles encroach less on the Frank-Starling mechanism for pressure adaptation.
- Chronic exercise training confers beneficial consequences for cardiac performance under stress.