[Stereological study of the absolute total volumes of the structural components of the myocardium in hypertrophy].

Wistar rats weighing 200 g were exposed in a low pressure chamber to daily adaptation to altitude hypoxia 8 hours long at an "altitude" of 8000 m. On the 40th experimental day the weight of the left heart ventricle was 41.5% higher as compared to controls. The volumetric and surface density of structural components of the myocardium were determined stereologically by light and electron microscopy, with their absolute total amounts and surfaces being calculated with respect to the ventricle on the whole. The total amount of myofibrila was shown to be steadily increased under hypertrophy, while the amount of mitochondria remained unchanged. However, the total mitochondrial surface augmented in parallel to an increase in the muscular component amount. It is suggested that myofibrillar amount and mitochondrial surface area may be viewed as controllable parameters in heart hypertrophy.