SERCA2A AND MITOCHONDRIAL CYTOCHROME-OXIDASE EXPRESSION ARE INCREASEDIN HEARTS OF EXERCISE-TRAINED OLD RATS

Aging of rats results in slower activities of calcium transport by car diac calcium adenosinetriphosphatase (ATPase) of the sarcoplasmic reti culum (SR) and mitochondrial cytochrome oxidase (COX). These enzyme ac tivities are faster after exercise training of previously sedentary ol d rats. Our purpose was to determine whether the expression of the gen es encoding SR calcium ATPase (SERCA2a) or COX is altered by exercise training. Old (24-mo-old) male Fischer 344 rats were assigned to SO (s edentary old) or EO (exercised old) groups and compared with younger ( 12-mo-old) sedentary rats (SM). EO rats were trained on a treadmill fo r 8-10 wk. SERCA2a and COX mRNAs were lower (P < 0.05) in SO compared with SM and EO, whereas glyceraldehyde 3-phosphate dehydrogenase (GAPD H) and cardiac alpha-actin mRNAs were Similar across groups. The immun oreactive protein contents of cardiac calcium ATPase, cytochrome c, sa rcomeric actin, and GAPDH followed the changes, when observed, in mRNA contents. Thus pretranslational mechanisms may be modified in some ge nes during aging and exercise training of previously sedentary old rat s.