出版社：Japan Society of Circulation Control in Medicine
摘要：Since oxidative stress is reported to be one of the mediators of synthesis of heat shock protein 70 (HSP70) induced by hyperthermia, we investigated the effects of N-2-mercaptopropionyl glycine (MPG), a diffusible antioxidant, in in vivo rabbit model of heat stress (HS) preconditioning. Three groups of rabbits were studied: Group I, control rabbits treated with anesthetic alone; Group II, rabbits subjected to HS by raising core temperature to 42°C for 15 min; Group III, given MPG (50mg/kg/hr i.v. ), beginning 30 min prior to HS and continued up to 15 min post HS. Twenty-four hours later, all animals were treated with 30 min of the left anterior descending coronary artery occlusion followed by 180 min of reperfusion under ketamine/xylazine anesthesia. Risk area was delineated by Evans blue and infarct size determined by tetrazolium staining. The risk area ranged from 59.3±5.8 % to 66.3±3.4 % with no significant difference among all the groups. Infarct size/area risk was 53.6±5.9 % in control rabbits, and decreased significantly to 26.7±4.3 % in the HS hearts. Treatment with MPG of HS rabbits resulted in a significant increase in the infarct size (48.6±11.8 %). The results show that prior HS significantly reduced infarct size (P<0.05) which was inhibited by MPG (P<0.01). Western blot analysis revealed significant synthesis of HSP70 in HS rabbit hearts and that synthesis was blocked with MPG. We conclude that oxidative stress is one of critical mediators of HS induced myocardial protection in vivo and trigger expression of HSP70.
