Brown C M, Collis M G
Eur J Pharmacol. 1983 Sep 30;93(3-4):277-82. doi: 10.1016/0014-2999(83)90148-6.
The aim of this study was to determine whether the adenosine receptor that inhibits adrenergic neurotransmission in the rabbit portal vein is of the A1 or the A2 subtype. Isometric contractions of the isolated vein were evoked by electrical field stimulation and by exogenous noradrenaline. Low concentrations of adenosine, and a number of analogues inhibited the response evoked by field stimulation but had no effect on those evoked by noradrenaline. The order of inhibitory potency was: L-N6-phenylisopropyladenosine (L-PIA) = N6-cyclohexyladenosine (CHA) = 5'-N-cyclopropylcarboxamide adenosine (NCPCA) greater than or equal to 5'-N-ethylcarboxamide adenosine (NECA) = 2-chloroadenosine greater than adenosine greater than D-PIA. The difference in potency between the stereoisomers L- and D-PIA was about 60 fold. The purine transport inhibitor dipyridamole potentiated the inhibitory effect of adenosine but not that of its analogues. The inhibitory responses evoked by adenosine and its' analogues were attenuated by the adenosine antagonist theophylline. These results indicate that adenosine selectively inhibits contractions of the rabbit portal vein evoked by adrenergic nerve stimulation via activation of an adenosine A1 receptor.
本研究的目的是确定在兔门静脉中抑制肾上腺素能神经传递的腺苷受体是A1亚型还是A2亚型。通过电场刺激和外源性去甲肾上腺素诱发离体静脉的等长收缩。低浓度的腺苷以及一些类似物抑制电场刺激诱发的反应，但对去甲肾上腺素诱发的反应没有影响。抑制效力顺序为：L-N6-苯基异丙基腺苷（L-PIA）= N6-环己基腺苷（CHA）= 5'-N-环丙基甲酰胺腺苷（NCPCA）≥5'-N-乙基甲酰胺腺苷（NECA）= 2-氯腺苷＞腺苷＞D-PIA。立体异构体L-PIA和D-PIA之间的效力差异约为60倍。嘌呤转运抑制剂双嘧达莫增强了腺苷的抑制作用，但未增强其类似物的抑制作用。腺苷及其类似物诱发的抑制反应被腺苷拮抗剂茶碱减弱。这些结果表明，腺苷通过激活腺苷A1受体选择性抑制肾上腺素能神经刺激诱发的兔门静脉收缩。
