肾上腺素受体腺苷酸环化酶系统在大鼠心肌缺血预适应中的变化

THE CHANGE OF ADRENERGIC RECEPTOR-ADENYL CYCLASE SYSTEM ON MYOCARDIAL ISCHEMIC PRECONDITIONING IN RATS

目的 :研究心肌缺血预适应时 β 肾上腺素受体腺苷酸环化酶系统各部分变化及意义。 方法 :选择SD大鼠 ,随机分成假手术组 (CON组 ) ,预适应组 (IP组 ) ,缺血 /再灌注组 (I/R组 )。以手术套管法造成左冠状动脉主干缺血及再灌注 ,损伤后取心脏用TTC法测梗塞面积 ,取血清测心肌酶改变 ,放射配基结合法测 β 肾上腺素受体 (β AR)密度及亲和力变化 ,生化法测AC活性变化 ,放免测cAMP水平。结果 :IP组较I/R组心梗面积明显缩小 (P <0 .0 1 ) ,心肌酶CK、CK MB、LDH明显降低 (P <0 .0 1 )。IP组受体密度较I/R组显著增加 (P <0 .0 1 ) ,两组受体解离常数无明显差异。IP组较I/R组AC活性增高 (P <0 .0 5) ,cAMP含量增加 (P <0 .0 1 )。结论 :缺血预适应对心脏具有保护作用 ,可缩小梗塞面积 ,减少心肌酶漏出 ,并使 β AR密度增高 ,cAMP产量增加 ,β

Aim: To study the varies and effects of ischemic preconditioning of myocardium on every part of adrenergic receptor adenyl cyclase system in rats in vivo . Methods: SD rats were randomly divided into three groups: CON group ( n =6), IP group ( n =12) and I/R group( n =12). Surgical procedure included intermittent left coronary artery occlusion and reperfusion. After the procedure, the hearts were extracted. We analyzed the infarct size by TTC staining, measured serum myocardial enzymes, studied the β AR Bmax and KD by radioligand binding assay of receptors(RAB), and checked the activity of AC and the content of cAMP by radioimmunoassay(RIA). Results: Infarct area were much smaller in IP group than in I/R group( P <0.05). CK,CK MB,LDH were significantly higher in I/R group( P <0.01). The Bmax of β AR in IP group were much higher than in I/R group( P <0.01). No difference of KD could be seen between IP and I/R group. In IP group, the activity of AC and the content of cAMP were higher than I/R group( P <0.05). Conclusion: Ischemic preconditioning can protect the heart from necrosis and reduce endo enzyme leakage. Ischemic preconditioning can increase the density of β AR, the activity of AC and the content of cAMP, which shows that the system of adrenergic receptor-adenyl cyclase system probably takes part in the protection of IP.