Effect of exercise and chronic administration of nandrolone decanoate on expression of rat heart sarcolemmal ATP- sensitive potassium channels

The anabolic androgenic steroids are known to stimulate muscle protein synthesis and hypertrophy. Cardiomyocytes have two types of ATP-sensitive potassium channels in sarcolemma (sarcKATP) and in mitochondria (mitKATP). Activation of the sarcKATP channels has been proposed to protect against ischemia-reperfusion injury. This study aimed to investigate the effect of nandrolone decanoate on the expression of sarcKATP channels in the presence and absence of exercise in rat heart. In this experimental study, 40 adult male rats were divided into five groups: control, vehicle, ND, exercise and exercise-ND group. Rats in the exercise group were submitted to a running program on a treadmill, 5 days a week for 10 weeks. In addition, rats in the ND and exercise-ND groups received a weekly intramuscular injection of ND (10 mg/kg) for 10 weeks. Expression of the KATP channel subunits (Kir6.2 and SUR2) was determined using the Western blotting method. ND administration had no effect on the expression of sarcKATP channel subunits in the sedentary group, while the chronic exercise significantly increased the expression of KATP channel subunits (P=0.01). Moreover, the ND administration significantly decreased the Kir6.2 (P=0.001) and SUR2 (P=0.05) subunits in the exercised animals. Chronic exercise and ND increases and decreases the expression of sarcKATP channels, respectively. The ND-induced expression decrement of channels is probably one of the mechanisms involved in the impairment of exercise-induced cardioprotection in rat heart.