An examination of pre- and postsynaptic alpha-adrenoceptors in the autoperfused rabbit hindlimb.
An examination of pre- and postsynaptic alpha-adrenoceptors in the autoperfused rabbit hindlimb.
复制标题
对自灌注兔后肢突触前和突触后α-肾上腺素受体的检查。
DOI：
10.1097/00005344-198009000-00011
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发表时间：
1980
影响因子：
3
通讯作者：
K. Starke
中科院分区：
文献类型：
--
作者：
H. Madjar;J. Docherty;K. Starke
采用育亨宾非对映异构体、山茱萸碱和其他对α 1-和α 2-肾上腺素选择性不同的药物检测兔后肢突触前和突触后α -肾上腺素受体。交感神经刺激和动脉内注射激动剂可引起血管收缩反应。α 2选择性拮抗剂rauwolsciine（10（-7）和10(-6)M）降低了注射去甲肾上腺素（α 1-和α 2混合激动剂）的反应，但对注射苯肾上腺素（α 1-选择性激动剂）没有反应；rauwolsciine （10(-6) M）实际上增强了神经介导的反应。雀花氨酸（α 1选择性拮抗剂）对激动剂和神经介导的反应具有同等效力。在另一系列的实验中，秋狼碱（10(-6)M）对二甲肾上腺素（α 2选择性激动剂）的拮抗作用较强，对α -甲基去甲肾上腺素和去甲肾上腺素（混合激动剂）的拮抗作用较弱，对苯肾上腺素的拮抗作用较强，对去甲肾上腺素和α -甲基去甲肾上腺素的拮抗作用较弱，对二甲肾上腺素的拮抗作用不强。月桂碱对神经效应反应的增强表明突触前α 2-肾上腺素受体介导的去甲肾上腺素释放的内源性自抑制作用。然而，与先前在兔肺动脉上的体外实验结果相比，由于突触后α 2-肾上腺素受体的存在，增强作用较小。
Pre- and postsynaptic alpha-adrenoceptors in autoperfused rabbit hindlimbs were examined employing the yohimbine diastereomers rauwolscine and corynanthine, as well as other drugs with varying selectivities for alpha 1-and alpha 2-adrenoceptors. Vasoconstrictor responses were elicited by sympathetic nerve stimulation and by intraarterial injection of agonists. The alpha 2-selective antagonist rauwolscine (10(-7) and 10(-6) M) reduced responses to injected noradrenaline (mixed alpha 1- and alpha 2-agonist) but not to injected phenylephrine (alpha 1-selective agonist); rauwolscine (10(-6) M) actually enhanced nerve-mediated responses. Corynanthine (alpha 1-selective antagonist) was about equipotent against agonist- and nerve-mediated responses. In another series of experiments, rauwolscine (10(-6) M) strongly antagonized the response to xylazine (alpha 2-selective agonist), antagonized the responses to alpha-methylnoradrenaline and noradrenaline (mixed agonists) less strongly, and did not affect the response to phenylephrine, Conversely, prazosin (alpha 1-selective antagonist, 10(-8) M) strongly antagonized phenylephrine, antagonized noradrenaline and alpha-methylnoradrenaline less strongly, and did not antagonize xylazine. Potentiation of neuroeffector responses by rauwolscine demonstrates the operation of an endogenous autoinhibition of noradrenaline release mediated by presynaptic alpha 2-adrenoceptors. However, in comparison with previous in vitro results on rabbit pulmonary artery, the potentiation was small due to the presence of postsynaptic alpha 2-adrenoceptors.