Effects of acute and chronic hypoxia on rat brain mitochondrial translation activity

AIM: To investigate the effect of simulated high altitude hypoxia on rat brain mitochondrial translation activity. METHODS: Animals were continuously exposed to simulated 4 000 m high altitude in hypobaric chamber for three days and forty days. Mitochondria of rat brain were isolated by homogenizing brain tissue and following centrifuging program. Protein translation activity in isolated mitochondria in vitro was measured with [³H]-Lencine incorporation method. Products labeled with [³⁵S]-methionine in isolated mitochondrial protein synthesis system in vitro were separated on SDS-PAGE and identified by autoradiography. RESULTS: Mitochondrial translation activity in vitro in acute hypoxia exposure were significantly lower than control(P< 0.01). Mitochondrial translation activity in chronic hypoxia exposure were significantly higher than that in acute hypoxia exposure(P< 0.05), but showed no statistical difference between chronic and control. No differences in electrophoretic-autoradiography pattern of -methionine incorporation into translational products was observed among three groups. CONCLUSION: These results indicated that acute hypoxia exposure depressed synthesis of mitochondrial protein encoded by mitochondrial DNA in vitro and the changes in mitochondrial protein synthesis were related with hypoxia exposure time.