Kunitada S, Ui M
Eur J Pharmacol. 1978 May 15;49(2):167-76. doi: 10.1016/0014-2999(78)90074-2.
Norepinephrine failed to increase plasma cyclic AMP when injected alone into fasted rats, in contrast with sharp increases elicited by isoproterenol, epinephrine or tyramine. In rats pretreated with 6-hydroxydopamine or cocain, however, there was significant increase in plasma cyclic AMP after norepinephrine injection, suggesting that the rapid neuronal catecholamine uptake was at least partly responsible for the lack of norepinephrine action. Phentolamine was very effective in enhancing the epinephrine-, norepinephrine- or tyramine-induced increase in plasma cyclic AMP but without effect on the isoproterenol-induced increase. Blockade of postsynaptic alpha-adrenoceptors, rather than of presynaptic receptors, is likely to be involved in the phentolamine potentiation, since it was even observed in rats treated with 6-hydroxydopamine or cocaine. A discussion is presented regarding the mechanism by which cyclic AMP generation is influenced by the alpha- and beta-adrenoceptor interaction on effector cell membranes.
与异丙肾上腺素、肾上腺素或酪胺引起的急剧升高相反，单独给禁食大鼠注射去甲肾上腺素未能使其血浆环磷酸腺苷（cAMP）升高。然而，在用6-羟基多巴胺或可卡因预处理的大鼠中，注射去甲肾上腺素后血浆cAMP显著升高，这表明快速的神经元儿茶酚胺摄取至少部分是去甲肾上腺素作用缺乏的原因。酚妥拉明在增强肾上腺素、去甲肾上腺素或酪胺引起的血浆cAMP升高方面非常有效，但对异丙肾上腺素引起的升高没有影响。酚妥拉明的增强作用可能涉及突触后α-肾上腺素能受体的阻断，而非突触前受体的阻断，因为在用6-羟基多巴胺或可卡因处理的大鼠中也观察到了这种现象。本文讨论了效应细胞膜上α-和β-肾上腺素能受体相互作用影响环磷酸腺苷生成的机制。
