Testosterone-propionate impairs the response of the cardiac capillary bed to exercise

Objective: Experimental application of anabolic-androgenic steroids and exe rcise training induce cardiac hypertrophy. This study quantifies for the fi rst time, on microscopical level, the adaptation of the cardiac capillaries and myocytes to the concomitant application of testosterone-propionate and exercise training. Methods: Female SPF-NMRI mice were studied over 3 and 6 wk. Experimental groups: (i) sedentary control (C); (ii) exercise (treadmi ll running, E); (iii) testosterone-propionate (TP); and (iv) testosterone-p ropionate+exercise (TPE). Morphometric parameters: 1) papillary muscles: ca pillary density, intercapillary distance, number of capillaries around a my ocyte, and minimal myocyte diameter; and 2) left ventricular wall: capillar y density and intercapillary distance. Results: Papillary muscle: A strikin g suppression of the exercise-induced improvement in capillary supply occur s in the testosterone-propionate+exercise groups over 3 and 6 wk. Exercise without drugs increases significantly (P < 0.05) the capillary density, sho rtens significantly (P < 0.05) the intercapillary distance, whereas it incr eases the number of capillaries around a myocyte. These alterations are not observed in the testosterone-propionate treated sedentary animals; e.g., c apillary density after 6 wk (mean values +/- standard deviation, capillarie s.mm(-2)): C: 4272 +/- 287. E: 5411 +/- 758, TP: 4221 +/- 364, and TPE: 399 7 +/- 397. Moreover, only in the testosrerone-propionate + exercise groups occurs a mild myocyte hypertrophy after both time periods: there is a trend toward hypertrophy (P < 0.1) in comparison with the C groups and a signifi cant hypertrophy (P < 0.05) in comparison with the E groups. Conclusions: T estosterone-propionate profoundly inhibits the exercise-induced augmented c apillarization, whereas (under training conditions) it leads to a mild myoc yte hypertrophy. The microvascular impairment could trigger an imbalance be tween the myocardial oxygen supply and demand, especially during physical e xercise.