SERCA2a and mitochondrial cytochrome oxidase expression are increased in hearts of exercise-trained old rats

Abstract

Aging of rats results in slower activities of calcium transport by cardiac calcium adenosinetriphosphatase (ATPase) of the sarcoplasmic reticulum (SR) and mitochondrial cytochrome oxidase (COX). These enzyme activities are faster after exercise training of previously sedentary old rats. Our purpose was to determine whether the expression of the genes encoding SR calcium ATPase (SERCA2a) or COX is altered by exercise training. Old (24-mo-old) male Fischer 344 rats were assigned to SO (sedentary old) or EO (exercised old) groups and compared with younger (12-mo-old) sedentary rats (SM). EO rats were trained on a treadmill for 8-10 wk. SERCA2a and COX mRNAs were lower (P < 0.05) in SO compared with SM and EO, whereas glyceraldehyde 3-phosphate dehydrogenase (GAPDH) and cardiac alpha-actin mRNAs were similar across groups. The immunoreactive protein contents of cardiac calcium ATPase, cytochrome c, sarcomeric actin, and GAPDH followed the changes, when observed, in mRNA contents. Thus pretranslational mechanisms may be modified in some genes during aging and exercise training of previously sedentary old rats.

Heat shock protein expression is increased in cardiac and skeletal muscles of Fischer 344 rats after endurance training

“…It is well established that endurance training provides benefits to the cardiovascular system and to skeletal muscles (Brooks & Fahey, 1985). The increased citrate synthase and cytochrome c oxidase activities in all heart sections (AT, RV and LV) after 16-20 weeks of treadmill running is consistent with the observation that endurance training has a stimulatory effect on oxidative metabolism in rat myocardium (Tate et al 1996). This observation demonstrates that the training parameters of our study were adequate to induce the expected exercise induced adaptations in the rat heart.…”

Exercise training improves functional post-ischemic recovery in senescent heart

“…However, heart weight-to-body weight ratio is not different between the two groups. This endurance exercise program, which consisted of rapidly walking, is moderate and does not induce cardiac hypertrophy, as previously reported (Tate et al, 1996). Citrate synthase activity is significantly increased soleus muscle from in 24 mo-trained rats compared to 24 mo-sedentary rats, indicating that the training program was effective in producing adaptation of active skeletal muscle oxidative metabolism (Table 1).…”

“…The following groups were used: sedentary senescent (24 mo-sedentary; n=10) and trained senescent (24 mo-trained; n=11) rats. The endurance exercise program consisted of treadmill rapidly walking for 12 weeks, after one week acclimatization to the motordriven treadmill (this included daily handling and walking on the treadmill), as previously described (Tate et al, 1996). The two first weeks, rats ran 5-10 min at 10-16 m/min at a 5% grade, 5 days/week.…”

Distinct load dependence of relaxation rate and diastolic function in Oryctolagus cuniculus and Ratus norvegicus

“…It should be emphasised that calcium regulatory proteins (Tate et al 1990(Tate et al , 1996 and myosin isoforms (Farrar et al 1988) are to some degree dependent on age and previous endurance performance. In our study this aspect can be excluded since all animals were instrumented at matched developmental ages and all animals had similar husbandry conditions.…”