Toda N, Kitamura Y, Okamura T
Department of Pharmacology, Shiga University of Medical Sciences, Ohtsu, Japan.
Invest Ophthalmol Vis Sci. 1995 Mar;36(3):563-70.
To determine if nitric oxide (NO) is involved in the relaxant response to nerve stimulation by nicotine and electrical pulses in dog external ophthalmic arteries (EOA) and internal ophthalmic arteries (IOA).
Changes in isometric tension were recorded in helical strips of the arteries, and the presence of perivascular nerve containing NADPH diaphorase was histochemically demonstrated.
Nicotine (10(-4) M, EOA and IOA) and transmural electrical stimulation (5 Hz, EOA) produced a slight or no contraction followed by a moderate relaxation in the strips contracted with prostaglandin F2 alpha. The contraction was abolished by alpha-adrenoceptor antagonists. The relaxation was abolished and the contraction was potentiated by NG-nitro-L-arginine (L-NA), a nitric oxide (NO) synthase inhibitor; the relaxation was reversed by L-arginine. Contractile response in L-NA-treated EOA was greater than in the IOA, and the relaxation was less in nontreated EOA. NO-induced relaxation and norepinephrine-induced contraction were not influenced by L-NA. There were plenty of nerve fibers visualized by NADPH diaphorase staining method in the adventitia of EOA and IOA, indicating the presence of NO synthase-containing nerves.
The neurogenic relaxation appears to be mediated by NO released from the vasodilator nerve in EOA and IOA. There is a reciprocal innervation in vasodilator nitroxidergic and vasoconstrictor noradrenergic nerves; functionally, the latter is more predominant in EOA than in IOA.
确定一氧化氮（NO）是否参与犬眼外动脉（EOA）和眼内动脉（IOA）对尼古丁和电脉冲神经刺激的舒张反应。
记录动脉螺旋条带的等长张力变化，并通过组织化学方法证明含NADPH黄递酶的血管周围神经的存在。
尼古丁（10⁻⁴ M，EOA和IOA）和经壁电刺激（5 Hz，EOA）在与前列腺素F2α收缩的条带中产生轻微收缩或无收缩，随后出现中度舒张。α-肾上腺素能受体拮抗剂可消除收缩。NO合酶抑制剂NG-硝基-L-精氨酸（L-NA）可消除舒张并增强收缩；L-精氨酸可逆转舒张。L-NA处理的EOA中的收缩反应大于IOA，未处理的EOA中的舒张反应较小。L-NA不影响NO诱导的舒张和去甲肾上腺素诱导的收缩。通过NADPH黄递酶染色法在EOA和IOA的外膜中可见大量神经纤维，表明存在含NO合酶的神经。
神经源性舒张似乎由EOA和IOA中血管舒张神经释放的NO介导。血管舒张性一氧化氮能神经和血管收缩性去甲肾上腺素能神经之间存在相互支配；在功能上，后者在EOA中比在IOA中更占主导地位。
