Hypoxic training increases metabolic enzyme activity and composition of alpha-myosin heavy chain isoform in rat ventricular myocardium.
Cardiac muscle adaptation is essential for maintaining physical capacity after ascending to high altitude. This study examines the effects of high altitude training on myocardial metabolic enzyme activity and composition of alpha-myosin heavy chain (MHC). Rats were randomly divided into normobaric sedentary (NS) and training (NT) groups, and hypobaric sedentary (HS) and training (HT) groups. HS and HT rats were exposed to hypobaric hypoxia (simulated 4,000-5,000 m) for 5 weeks (24 h/day), and HT rats simultaneously received swim training. Hypoxia exposure for 5 weeks led to a decrease in succinate dehydrogenase (SDH) and citrate synthase (CS) activities in the left ventricle (LV), and a decrease in CS, hexokinase (HK) and total lactate dehydrogenase (LDH) activities in the right ventricle (RV) (p < 0.05, HS vs. NS). Furthermore, 1 h/day swim training during hypoxia exposure enhanced the CS activity in LV and the SDH and CS activities in RV (p < 0.05, HT vs. HS). The percentages of alpha-MHC in both ventricles in HT were higher than those in HS (p < 0.05). We conclude that exercise training at high altitude is beneficial for cardiac muscle adaptation to hypoxia by increasing activities of enzymes and percentage of alpha-MHC. This may contribute to improved cardiac function and work capacity at high altitude.
Cai
Ming-Chun
MC
Department of Pathophysiology and High Altitude Physiology, Key Laboratory of High Altitude Medicine, Ministry of Educative, Third Military Medical University, Chongqing, China.
Huang
Qing-Yuan
QY
Liao
Wei-Gong
WG
Wu
Zhou
Z
Liu
Fu-Yu
FY
Gao
Yu-Qi
YQ
D000222:Adaptation, Physiological; D000532:Altitude Sickness; D000704:Analysis of Variance; D000818:Animals; D002950:Citrate (si)-Synthase / Q000378:metabolism; D006801:Humans; D000860:Hypoxia / Q000201:enzymology* / Q000378:metabolism / Q000503:physiopathology*; D008297:Male; D009206:Myocardium / Q000473:pathology; D018995:Myosin Heavy Chains / Q000378:metabolism*; D009218:Myosins / Q000502:physiology; D010805:Physical Conditioning, Animal / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013385:Succinate Dehydrogenase / Q000378:metabolism
D013385:Succinate Dehydrogenase; D002950:Citrate (si)-Synthase; D018995:Myosin Heavy Chains; D009218:Myosins