Adaptive Changes And Mechanisms Of Heart And Skeletal Muscle In Rats Exposed To Chronic Hypoxia Alone Or Hypoxia-combined Exercise

Rapid ascent to a high altitude environment decreases working performance of the sea level residents, which is a general phenomenon of poor acclimatization to hypoxia. Active search for the ways of promoting acclimatization to high altitude environments arouses many researchers'concern in the field of high altitude medicine and biology. It is well known that physical exercise at plain is helpful to acclimatization to high altitude. Recently, our research results suggested that moderate physical training at high altitude promoted acclimation to high altitude through induction of increment in capillary density, decrease in the blood viscosity and increase in the cardiac function. Previous researches in this field chiefly focused on observation of structures and tissues at the levels of animals and of organs, but little is known about the basic mechanisms regarding biochemistry and molecular biology. The main factor that high altitude environments affect people is hypoxia. Equilibrium between energy production and energy utilization is the most important for the acclimatization. Therefore, we conducted systemic researches into the influence of hypoxia-combined exercise on energy metabolism at the levels of tissue for the purpose of further understanding the mechanisms of exercise training promoting acclimatization at high altitude. We used swimming training of rats in hypobaric hypoxia chambers as the model of simulated hypoxia-combined exercise, and to study the acclimative changes of energy metabolism and related mechanism. Wistar rats were divided into 4 groups: normoxic control(C); hypoxia(H); exercise(E) and hypoxia-combined exercise(HE). The composition of myosin heavy chain isoform(MHC), metabolism enzyme activity, energy-sensing/signaling proteins AMPK, GLUT4 and mitochondrial function in rat ventricles and skeletal muscle were tested by such techniques as sodium dodecyl sulfate polyacrylamide gel electropheresis, isotope incorporation, western blotting and other biochemical methods. The main results and conclusions are as follows:...