游泳训练对大鼠心肌α_1肾上腺素受体及其亚型的影响

EFFECT OF SWIM TRAINING ON MYOCARDIAL α_1-ADRENOCEPTOR AND ITS SUBTYPES IN RATS

采用放射配体结合实验观察大鼠游泳训练8周后心肌中α_1肾上腺素受体(α_1受体)及其亚型的变化。^(125)I-BE 2254 Scatchard分析显示α_1受体的B_(max)由对照组(n=5)的43.3±5.5fmol/mg增加到训练组(n=5)的75.0±8.2fmol/mg,(P<0.02),K_D值无显著改变。WB4101竞争抑制曲线显示大鼠心肌中的α_1受体可分成与WB 4101 高亲和性的α_(1a)亚型与低亲和性的α_(1b)亚型,训练组心肌中α_(1a)亚型所占比例由对照组的28.5%增加到39.5%。结果提示,运动后心肌中α_1受体尤其α_(1a)亚型数量增加,这种改变可能与运动性心肌肥大有关。

Changes of a_1-adrenoceptor and its subtypes in myocardium were studied by radioligand binding assay inrats which received swim training for 8 weeks. The ^(125)I-BE^(2254) scatchard analyses showed that Bmax inthe training group (n = 5) was significantly increased from 43.3±5.6 fmol/mg in the control group (n = 5)to 75.0 ± 8.2 fmol/mg (p<0.02), while K_D was not changed. Two-site analysis of inhibition of specific^(125)I-BE binding by WB4101 showed there existed high affinity site (a_1 subtype) and low affinity site (a_(1b)subtype). The a_(1a) subtype accounted for 28.5% of the total a_1-adrenoceptor in the control group, but itincreased to 39.5% in the training group. The results indicate that a_1-adrenoceptor, especially a_(1a) subtype,increased after swim training, which might link to myocardial hypertrophy in physical exercise.