Chiu K W, Sham J S
Comp Biochem Physiol C Comp Pharmacol Toxicol. 1985;81(2):445-50. doi: 10.1016/0742-8413(85)90035-0.
Cardiac adrenergic receptors in snakes were examined using an isolated atria preparation of Naja naja and Ptyas korros. Treatments included an examination of the atrial responses to selective alpha- and beta-adrenergic agonists and antagonists. In both species, both phenylephrine and isoproterenol produced dose-dependent increases in the atrial beating rate and tension. Phenylephrine-induced increases were characterized with a high affinity and low affinity components. These positive chronotropic and inotropic effects produced by phenylephrine and isoproterenol were abolished with propranolol and in the phenylephrine-induced response phentolamine also attenuated the low affinity response and blocked the high affinity response. With catecholamines depletion via 6-OH dopamine or reserpine, the high affinity component in the phenylephrine-induced response was no longer observed. It is concluded that beta-adrenoceptors are the predominant post-synaptic adrenoceptors in snake atria. Stimulatory presynaptic alpha-adrenoceptors for modulating noradrenaline release may also be present.
使用眼镜蛇和滑鼠蛇的离体心房标本对蛇的心脏肾上腺素能受体进行了研究。实验处理包括检测心房对选择性α和β肾上腺素能激动剂及拮抗剂的反应。在这两个物种中，去氧肾上腺素和异丙肾上腺素均可使心房搏动频率和张力呈剂量依赖性增加。去氧肾上腺素诱导的增加表现为高亲和力和低亲和力两个组分。普萘洛尔可消除去氧肾上腺素和异丙肾上腺素产生的这些正性变时和变力作用，在去氧肾上腺素诱导的反应中，酚妥拉明也可减弱低亲和力反应并阻断高亲和力反应。通过6-羟基多巴胺或利血平使儿茶酚胺耗竭后，去氧肾上腺素诱导反应中的高亲和力组分不再出现。得出的结论是，β肾上腺素能受体是蛇心房中主要的突触后肾上腺素能受体。也可能存在调节去甲肾上腺素释放的刺激性突触前α肾上腺素能受体。
