Dynamics of the hypertrophied left ventricle in the rat. Effects of physical training and chronic pressure load.

Left ventricular hypertrophy of about 40% was produced in rats by narrowing one renal artery (Goldblatt II) and of about 6% by swimming-training for 2 hours a day for 14 weeks. The dynamics of the hypertrophied ventricles were investigated by means of the isovolumic systolic and diastolic pressure-volume relations, the stress development during afterloaded and isovolumic contractions, and the force-velocity relation. The following results were obtained: The performance of the whole hypertrophied ventricle is increased. The developed stress and the maximum rate of stress development are enhanced, probably as a consequence of the increased density of the contractile proteins. The maximum shortening velocity can be reduced at the same time.