| The heart is one of the vital organs in the human’s life. It plays an important role in maintaining human exercise and life activities. Exercise is a kind of pathophysiological stimulu. Different intensity exercise have different effects on heart function. Appropriate exercise would improve heart function, but excessive exercise may have an adverse effect on the heart.Under intervention of different intensity exercise factors, what adaptive change happened to the oxidative substrates of myocardial mitochondria such as fatty acid and glucose, which kinds of substrates were in a dominant position, and which kinds of effects did the utilization of mitochondrial substates produce, and the molecular mechanism in them.Little studies devote this area at present. In this study, the mechanism of myocardial energy utilization by different intensity exercise would be understanded thoroughly from the level of cell biology and molecular biology. It would be of great importance in investigating a variation rule in cardiovascular system function. It also would be of great importance in formulating a scientific and rational exercise program.To analysis the myocardial energy substrate, we used "in-situ method",which did not require separate the organelles, only required to apply the appropriate agent for selective permeability on myocardial fibers. Thereby we implemented a kind of titrion step which was designed specially.Then the analysis of kinds of mitochondrial complexes step by step would be achieved. Peroxisome proliferators activated receptorα(PPARα) and Akt2 are the genes which play an important role in glucose and lipid metabolising. PPARα is abundantly expressed in cardiomyocytes. Itinvolved in lipid metabolism of the cardiomyocytes. Its activition is beneficial to uptake and utilization myocardial fatty acid. Akt2(serine/threonine protein kinase) is highly expressed in the myocardium. Its activition is beneficial to uptake and utilization myocardial glucose.The issue constructed an exersice model by Bedford. 19 male Sprague- Dawley rats were randomly divided into sedentary control group(C, N=7), moderate intensity exercise group(78%VO2max)(ME, N=6)and low intensity exercise group(68%VO2max)(LE, N=6). The myocardial mitochondrial respiratory function was measured in situ method when the fatty acid(Palmitoylcarnitine/Malate(Pal/Mal),Octanoylcarnitine(Oct)) and carbohydrate(Pyruvate(Pyu), Glutamate(Glu),Succinate(Suc)) were used as substrates. The changes of PPARα and Akt2 gene expression were determined by RT-PCR and Western Blot.The result showed that: ① Compared with C and LE, when the fatty acid(Pal/Mal, Oct) were used as substrates, the respiration ratio of ME had an upward trend, but not significantly. ② Compared with C, when the carbohydrates(Pyu and Glu)were used as substrates, the respiration ratio of ME increased significantly(P <0.05). ③ Compared with C, when P/M was used as substrates, the respiration control rate(RCR)(P <0.01) and 3 state respiration(T3)(P <0.05) of ME increased significantly. No significant difference was found between C and LE. ④ Compared with C and LE, the PPARαand Akt2 gene expression of ME and LE had an upward trend.Compared with C, the protein PPAR α and Akt2 expression were significantly increased in LE and ME.Therefore, we concluded that: ME could improve the function of myocardial mitochondria. It had a potential trend on optimizing myocardial energy metabolism. It could made myocardial metabolic conversion from fatty acid to the direction of glycolysis and glucose oxidation. |
PDF Full Text Request