Swim exercise training and adaptations in the antioxidant defense system of myocardium of old rats:relationship to swim intensity and duration

摘要

We examined a suitable swim program of different intensities and durations that could evoke changes in the myocardial antioxidant capacity in 22-month-old rats.Male rats(Rattus norvegicus)were assigned to either a sedentary control(SE-C)group or one of six trainee groups.Animals were swim-exercised for 4 weeks with either 20 min or 40 min/ day,and three intensities,low,moderate and high.Low-intensity at 20 min/day elicited maximum swim velocity(S_v)and endurance capacity(P<0.05).While serum total cholesterol,triglyceride and low-density lipoprotein(LDL-C)levels were significantly reduced,high-density lipoprotein(HDL-C)showed an increase(P<0.05)in low-intensity trained rats(20 min/day)over SE-C.Notable reduction in blood lactate was also evident.Exercise training significantly increased superoxide dismutase(Mn-SOD),decreased lipid peroxidation products,malondialdehyde and lipofuscin in the left and right ventricles.Increased Mn-SOD with concomitant decrease in lipofuscin in left ventricle was significantly greater than in right ventricle.Moderate- to high-intensity exercise was not effective in either reducing lipid peroxidation products or elevating Mn-SOD activity.These data suggest that swim training at low-intensity of 20 min/day is beneficial as a major protective adaptation against oxidative stress in old myocardium.