Anabolic steroids alter the haemodynamic effects of endurance training on the canine left ventricle.

The effects of six week, high-dose anabolic steroid treatment (methandienone, 1.5 mg/kg/day) on the changes in left ventricular function induced in dogs by endurance training were studied by a catheterization technique under anaesthesia. Pacing, isoproterenol and dextran infusions were used as loading tests (respectively). Dogs were randomized into an exercise group (EG, n = 7) and an exercise-steroid group (ESG, n = 7), the latter receiving anabolic steroids as well as participating in the training program. In a standardized submaximal exercise test, the heart rate of unanesthetized dogs was lower both in the EG (p less than 0.001) and in the ESG (p less than 0.01) after the training period than before it. In the EG the resting systemic vascular resistance (SVR) before haemodynamic interventions was lower (p less than 0.05) and left ventricular stroke work (SW) was higher (p less than 0.05) after the training period than before. In the ESG, left ventricular ejection fraction (EF) decreased with training and anabolic steroid treatment (p less than 0.05). After the training period isoproterenol increased the maximum velocity of the cardiac contractile element significantly more (p less than 0.05) in the EG than in the ESG. Also SW increased in the EG (29%, p less than 0.001), but not in the ESG (-11%, NS). Endurance training increased the left ventricular end-diastolic and stroke volumes during isoproterenol infusion, but this training effect was attenuated by simultaneous anabolic steroid treatment (p less than 0.05 between the groups in both cases). During the isoproterenol test SVR decreased less in ESG than in EG (p less than 0.05 between).(ABSTRACT TRUNCATED AT 250 WORDS)