Ohkubo H, Chiba S
Department of Ophthalmology, Shinshu University School of Medicine, Matsumoto, Japan.
Curr Eye Res. 1988 Jun;7(6):607-13. doi: 10.3109/02713688809031817.
Both periarterial electrical stimulation (ES) and intraluminal application of norepinephrine (NE) produced a vasoconstriction in the isolated canine ophthalmic artery (OA). The ES-induced vasoconstrictor response was markedly inhibited by treatment with tetrodotoxin and slightly but significantly depressed by xylazine, a selective alpha-2 adrenoceptor agonist. Moreover, the ES-induced response was enhanced by either DG-5128, a selective alpha-2 adrenoceptor antagonist, or angiotensin II. The inhibitory effect of bunazosin on the ES-induced response was significant, but it was rather small compared with that on the NE-induced response. The NE-induced constriction was not affected by xylazine and DG-5128, but significantly enhanced by angiotensin II. These results indicate that (1) the ES-induced response is mediated via sympathetic nerve activation, (2) there are inhibitory prejunctional alpha-2 adrenoceptors, (3) there are more postjunctional alpha-1 than postjunctional alpha-2 adrenoceptors in canine OAs, and (4) prejunctional angiotensin II receptors may exist in isolated OA preparations.
动脉周围电刺激（ES）和腔内应用去甲肾上腺素（NE）均可使离体犬眼动脉（OA）产生血管收缩。河豚毒素处理可显著抑制ES诱导的血管收缩反应，而选择性α-2肾上腺素能受体激动剂赛拉嗪可使其轻微但显著降低。此外，选择性α-2肾上腺素能受体拮抗剂DG-5128或血管紧张素II均可增强ES诱导的反应。布那唑嗪对ES诱导反应的抑制作用显著，但与对NE诱导反应的抑制作用相比相对较小。NE诱导的收缩不受赛拉嗪和DG-5128的影响，但血管紧张素II可使其显著增强。这些结果表明：（1）ES诱导的反应是通过交感神经激活介导的；（2）存在抑制性节前α-2肾上腺素能受体；（3）犬眼动脉中节后α-1肾上腺素能受体比节后α-2肾上腺素能受体更多；（4）离体眼动脉制剂中可能存在节前血管紧张素II受体。
