预缺血对家兔缺血心脏的保护作用及其对心肌腺苷受体特性的影响(英文)

Protective effect of preconditioning on ischemic heart and characterization of adenosine receptors in ischemic rabbit hearts

分析腺苷受体在预缺血对心肌保护中的作用和心肌腺苷受体的特性.方法:1)在18只麻醉家兔,结扎左冠脉前降支以诱发心肌缺血;2)心外膜ST段抬高作为急性心肌缺血的指标;3)用[~3H]腺苷测定心肌腺苷受体.结果:1)缺血60 min时,心外膜ST段抬高(13.9±0.6 mV)明显高于预缺血后再缺血60 min时(3.1±0.5 mV);2)在预缺血后再缺血心室肌细胞膜,腺苷受体密度(B_(max))高于单独缺血组和对照组(B_(max)分别为602±40,348±28和335±30 pmol/g protein),但缺血组的心室肌细胞膜腺苷B_(max)未增高;3)各组的心室肌细胞膜的腺苷受体亲合力(K_d无显著差异(K_d分别为181±18,169士21和196±24 nmol·L^(-1)).结论:预缺血时腺苷受体激活和腺苷受体数增多是腺苷对缺血心肌保护作用的基础.

To assess the role of adenosine receptors in the cardioprotective effect of preconditioning and the characterization of adenosine receptors in heart. METHODS: In 18 anesthetized rabbits, myocardial ischemia was induced by occlusion of left descending coronary artery. ST segment elevation in epicar-dial electrogram was used as a criterion of acute ischemic injury. Myocardial adenosine receptors were measured using [3H]adenosine ligand. RESULTS:After 60-min ischemia, epicardial ST segment elevation was higher in ischemia group (13.9±0.6mV) than in the ischemic preconditioning group (3.1 ±0.5mV). In membranes of the ventricular myocytes prepared from ischemic-precondi-tioning group, the density of adenosine receptors was higher than that of ischemia and sham ischemia groups (Bmax being 602±40, 348±28, and 335±30pmol/g protein, respectively). Affinity of the receptors for the [3H] adenosine was not different in the 3 groups (Kd being 181±18, 169±21, and 196 ±24nmol.L-1,respectively). CONCLUSION:Activation of adenosine receptors along with an increase in adenosine receptor density during ischemic-preconditioning provides the basis for adenosine to exert its protective effect on the ischemic heart.