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采用［１２５Ｉ］ＢＥ２２５４放射配体结合实验和离体灌流左心房收缩功能实验，比较１２月龄与３月龄大鼠心脏α１肾上腺素受体（α１－ＡＲ）三种亚型分布及其介导的正性变力效应的差别．结果显示与３月龄大鼠相比，１２月龄大鼠：（１）心脏α１－ＡＲ最大结合容量显著减少；去甲肾上腺素（ＮＥ）通过激动α１－ＡＲ引起的左心房累积浓度－收缩效应曲线显著右移；（２）（＋）尼古地平，ＢＭＹ７３７８和ＷＢ４１０１的高亲和性位点所占百分比显著下降；（３）氯乙基可乐定预处理使ＮＥ引起的左心房最大收缩效应的下降幅度，以及舍吲哚，ＢＭＹ７３７８和ＷＢ４１０１拮抗ＮＥ介导正性变力效应的ｐＡ２值均无显著差异．提示１２月龄大鼠较３月龄大鼠心脏α１－ＡＲ总数减少，且以α１Ａ－和α１Ｄ－ＡＲ亚型更为显著；α１－ＡＲ介导的正性变力效应明显降低，α１Ｂ－ＡＲ的功能效率降低最为明显．
[125I] BE2254 radioligand binding assay and left atrial systolic function in vitro were used to compare the distribution of α1-adrenoceptor (α1-AR) subtypes in 12-month-old and 3-month- The positive variation effect of the difference. The results showed that the 12-month-old rats had (1) a significant decrease in the maximal binding capacity of cardiac α1-AR compared with 3-month-old rats; the left atrial cumulative concentration-contraction induced by norepinephrine (NE) (2) The percentage of high affinity sites of (+) nicotine, BMY7378 and WB4101 decreased significantly; (3) The preconditioning with clonidine There was no significant difference in the decrease of the effect and the pA2 values of sertindole, BMY7378 and WB4101 antagonistic NE-mediated positive force effect. The results showed that the total α1-AR in 12-month-old rats was significantly lower than that in 3-month-old rats, and the α1A- and α1D-AR subtypes were more significant. The α1-AR- The most obvious reduction in functional efficiency.