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大鼠左心房al受体及其亚型对p受体正性变力效应的影响

张幼怡, 禹更生, 陈明哲, 韩启德

(北京医科大学第三医院血管医学研究所，北京100083)

摘要

本文用放射配体结合实验研究了al一肾上腺素受体(a,-AR)及亚型在大鼠左心房的分布。结果表明，大鼠左心房a,-AR有atA与a,B两种亚型，a,、亚型约占1/3, a,B亚型占2/3。离体灌流左心房功能实验结果表明，a,-AR不同亚型对(3肾上腺素受体((3-AR)所介导的正性变力反应具有不同性质的协同作用。当酚妥拉明10 pmol/L同时阻断a,、与al。亚型时，NE(同时激动a,一与(3-AR)的剂量一收缩效应曲线显著左移，当用CEC 20 wmol/L预处理以阻断aiB亚型时，NE的剂量一收缩效应曲线则显著右移，而用WB4101 1 nmol压阻断aiA亚型后，NE的剂量一收缩效应曲线出现左移;此外，当用苯肾上腺素激动a,-AR时，异丙肾上腺素的剂量一收缩效应曲线亦显著右移。提示atA亚型可抑制(3-AR介导的正性变力效应，而a,。亚型则可增强(3-AR所介导的反应，但当a,-AR的上述两种亚型同时激动时，则以a,、亚型的调节作用为主。

关键词： #alpha#l肾上腺素受体; 日肾上腺素受体; 受体亚型; 心脏; 正性变力效应

EFFECT OF al一 ADRENOCEPTOR SUBTYPES ON S-ADRENOCEPTOR MEDIATED POSITIVE INOTROPIC RESPONSE IN RAT LEFT ATRIA

ZHANG YOU-YI , YU GENG-SHENG , CHFNG MTNCi-ZHF ANT) HAN OT_DF (CHTT)F HAN

Section of Primates Cognitive Brain Research,Kunming Institute of Zoology,the Chinese Academy of Sciences.Kunming 650223,Yunnan

Abstract

The distribution of the #aLpha#l-adrenoceptor (#alpha#l-AR) subtypes and the effects of activation of al一AR subtypes on the#beta#adrenoceptor(#beta#AR) mediated positive inotropic response were investigated. The radioligand binding assays indicated that the Bmex and Kd
values were 11. 7士18 fmol/mg·protein and 8 6. 0士9. 6 pmol/L respectively. Pretreatment of the preparations with 20 }imol/L chloroethylclonidine (CEC) which inactivated a1#beta# subtype，decreased the B. to 45. 7士5. 2 fmol/mg·protein (P<0. 0l).
The inhibition curves of 5-methyl-urapidil were best fitted to two site model and indicated that a1A subtype took 28. 5%of total 12sIBE specific binding sites. In the functional experiments，norepinephrine (NE) induced a positive inotropic response in a concentration dependent manner by activation of both#beta#and #alpha#l-AR. The concentration-response curves (CRC) for NE were shifted rightward after the pretreatment of the preparations with 20 pmol/L CEC，but leftward in the presenece of I nmol/L WB4101. In the presence of 10 }tmol/L phentolamine which inactivated both #alpha#l-AR subtypes，the CRC for
NE were shifted leftward. When al一AR was activated by phenylephrine the CRC for isoproterenol (selective#beta#AR agonist) were shifted rightward. The results suggested that the #alpha#1#beta# subtype enhanced while the #alpha#1A subtype inhibited the (3-AR mediated positive inotropic response. When both alA and #alpha#1#beta# subtypes were activated simultaneously the #alpha#1A subtype show dominate role.

Key words: a,-adrenoceptor; ;S-adrenoceptor;;receptor subtype

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引用本文：

张幼怡, 禹更生, 陈明哲, 韩启德. 大鼠左心房al受体及其亚型对p受体正性变力效应的影响[J]. 生理学报 1994; 46 (5): .

ZHANG YOU-YI , YU GENG-SHENG , CHFNG MTNCi-ZHF ANT) HAN OT_DF (CHTT)F HAN. EFFECT OF al一 ADRENOCEPTOR SUBTYPES ON S-ADRENOCEPTOR MEDIATED POSITIVE INOTROPIC RESPONSE IN RAT LEFT ATRIA. Acta Physiol Sin 1994; 46 (5): (in Chinese with English abstract).