Age-related differences in the effect of running training on cardiac Myosin isozyme composition in rats.
We examined the effect of running training on age-related changes in cardiac myosin isozyme composition in rats. Female Fischer 344 rats (6, 12, 20, and 27 months old) were divided into two groups: sedentary control and trained. The trained group rats were trained by treadmill running for up to 60 minutes per day, 5 days per week for 8 weeks at up to 30 m per minute. In sedentary control rats, the proportion of V1 myosin, that is, alpha-myosin heavy chain (MyHC) isoform, decreased progressively from 6 to 27 months of age. In the younger age groups (6 or 12 months old), there was a shift from V1 myosin to V3 myosin (beta-MyHC isoform) in trained hearts. However, the training program did not induce a cardiac myosin isozyme transition in older rats (20 or 27 months old). These results suggest that the mechanisms mediating the responses of cardiac muscle to running training alter during aging.
Department of Exercise Physiology, International Budo University, Chiba, Japan. MachidaS@missouri.edu
Shuichi
S
Machida
Hisaya
H
Tsujimoto
Hideki
H
Suzuki
Norikatsu
N
Kasuga
Keizo
K
Kobayashi
Mitsuo
M
Narusawa
D000375:Aging / Q000502:physiology*; D000818:Animals; D005260:Female; D009206:Myocardium / Q000201:enzymology*; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D011916:Rats, Inbred F344; D012420:Running / Q000502:physiology*; D024723:Ventricular Myosins / Q000032:analysis*
D024723:Ventricular Myosins