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Histochemical and morphological observations on rat myocardium after exercise

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Effects of seven levels of chronic physical activity on the metabolic and morphologic characteristics of left ventricular myocardium of adult male albino rats were investigated.

Treatments included sedentary control; voluntary running; short-duration, high-intensity running; medium-duration, moderate-intensity running; long-duration, low-intensity running; electric stimulus control; and endurance swimming. Excluding the controls, the animals were trained 5 days per week for 8 consecutive weeks. Food and water were providedad libitum to them. Fifty-six animals comprised the final sample.

Histochemical techniques were used to evaluate the relative glycogen, fatty acid, SDH and LDH concentrations in the cardiac fibers. Each stain was measured objectively, using a photometer. A Hematoxylin and Eosin stain was employed to rate morphologic features. These sections were evaluated subjectively on the basis of presence or absence of lesions.

Physical training for 8 weeks was sufficient to produce metabolic adaptations in the rats. The trained animals gained 37.4 % less body weight than did the sedentary controls (P < 0.05). However, neither histochemical nor morphological changes had occurred to the hearts of these animals consequent to the 8 weeks training programs. Apparently, the myocardial tissues examined, from the trained animals, contain the enzymes, SDH and LDH, and the substrates, glycogen and fatty acids, in amounts greater than that needed to cope with the exercise stress afforded by these training programs.

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Ruhling, R.O., van Huss, W.D., Heusner, W.W. et al. Histochemical and morphological observations on rat myocardium after exercise. Int. Z. Angew. Physiol. Einschl. Arbeitsphysiol. 31, 305–313 (1973). https://doi.org/10.1007/BF00693715

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Key words

  • Exercise
  • Histochemistry
  • Metabolism
  • Myocardium-Pathology