内源性阿片物质参与大鼠缺血预处理的心肌保护作用

实验以离体灌流的ＳＤ大鼠心脏为模型,用ｋ特异性拮抗剂的ＭＲ２２６６研究ｋ阿片受体的阻断与缺血预处理的关系,用放射免疫分析法研究ＩＰ及长时间缺血对心肌强啡肽Ａ１－１３浓度的影响,探索Ｋ阿片物质在ＩＰ过程中的作用和地位。

Involvement of endogenous opioids in cardioprotective effects of ischemic preconditioning in the isolated rat heart

In the present stUdy, the relationship between the blockade Of K-opioid receptor and ischemic preconditioning (IP) was examined and the effect of lP and prolonged ischemia on levels of dynorphin A1-13 (Dyn A1-13) in cardiac muscle in isolated perfused rat heart was investigated. The results are as follows: (1) IP reduced the severity of ischemia/reperfusion arrhythmia (P < 0.05) and infaret size (P < 0.01 ), but had no significant effect on heart rate and coronary flow (p > 0.05); (2) MR2266, K opioid receptor antagonist, reduced the severity of ischemia/reperfusion arrhythmia(P < 0.05)and infarct size (P < 0.01 ), and also enhanced the recovery of coronary flow, but had no significant effect on heart rate (P > 0.05); and (3) prolonged ischemia decreased the levels of Dyn A1-13 (P < 0.05), which was more marked in the unpreconditioned hearts. The results suggest: (1 ) MR2266 can "mimic" cardioprotective effect of IP in reducing the severity of arrhythmias and limiting infarct size of cardiac muscle; (2)ischemia causes release of endogenous K opioids , which can be attenuated by IP; and (3) the cardioprotective effects of IP in rat heart involves endogenous K opioids.