Anabolic steroids impair the exercise-induced growth of the cardiac capillary bed.

BACKGROUND

Concomitant application of anabolic-androgenic steroids and physical exercise can induce cardiac hypertrophy. These experiments investigate the still unknown response of the cardiac myocytes and capillaries to the combined influence of various anabolic steroids and muscular exercise.

METHODS

Female SPF-NMRI mice were divided into the following groups: a) sedentary control, b) exercise (treadmill running); c) sedentary receiving Dianabol; d) exercise + Dianabol; e) exercise + Oral-Turinabol. After 3 and 6 weeks the left ventricular papillary muscles were studied morphometrically. Evaluated variables: minimal myocyte diameter, number of capillaries around a single myocyte, capillary density and intercapillary distance.

RESULTS

Only the anabolic steroids + exercise groups showed a mild myocyte hypertrophy. In contrast, only exercise alone caused a significant increase of the capillary density after both experimental periods; e.g. capillary density after 6 weeks (capillaries/mm2, mean values +/- standard deviation, p < 0.05): control (4,272 +/- 287), exercise (5411 +/- 755), dianabol (4,004 +/- 333), dianabol + exercise (4,076 +/- 403), oral-turinabol + exercise (4,053 +/- 306). Moreover, unlike all other regimens, only exercise alone shortened the intercapillary distance. Finally, exercise without drugs induced the greatest increase in the number of capillaries around a single myocyte.

CONCLUSIONS

Anabolic steroids combined with exercise: 1) induce mild hypertrophy of the cardiac myocytes, 2) impair the cardiac microvascular adaptation to physical conditioning. The microvascular impairment may cause a detrimental alteration of the myocardial oxygen supply, especially during muscular exercise.