Hayashi E, Yoshitomi T, Ishikawa H, Hayashi R, Shimizu K
Department of Ophthalmology, Kitasato University School of Medicine, Kanagawa, Japan.
Jpn J Ophthalmol. 2000 May-Jun;44(3):214-20. doi: 10.1016/s0021-5155(99)00215-4.
Isopropyl unoprostone (unoprostone), a prostaglandin F(2 alpha) (PG F(2 alpha))-related compound, is widely used for treatment of glaucoma in Japan and is reported to have effects on ocular circulation. To investigate the action of this drug, we have studied the effect of unoprostone on the isolated rabbit ciliary artery.
Under microscopic observation, ciliary arteries were prepared from rabbit eyes and mounted in a myograph system. The effects of unoprostone on the isolated rabbit ciliary artery were investigated in vitro using isometric tension recordings.
Exogenously applied PG F(2 alpha) but not unoprostone evoked contraction in the rabbit ciliary artery. After precontraction with excess-K solution, unoprostone evoked dose-dependent relaxation. The relaxation was not blocked by 10 microM/L N(G)-nitro-L-arginine methylester (L-NAME), 1 microM/L 8-37 calcitonin gene-related peptide (8-37 CGRP) or 10 microM/L indomethacin. Moreover, unoprostone could induce relaxation even in preparations without endothelium. The relaxation induced by diltiazem was greater in muscle precontracted in excess-K solution than that precontracted by 10 microM/L histamine. On the other hand, unoprostone induced a similar amplitude of relaxation in muscles precontracted by either drug.
These results indicate that unoprostone acts directly to relax rabbit ciliary artery. The relaxation was not dependent on the endothelium and was not caused by intrinsic prostoglandins CGRP, or nitric oxide. Moreover, the relaxation was different from that caused by a Ca(2)+ antagonist. The mechanism for this relaxation is not yet determined.
异丙前列素（unoprostone）是一种与前列腺素F(2α)（PG F(2α)）相关的化合物，在日本被广泛用于治疗青光眼，据报道对眼循环有作用。为研究该药物的作用，我们研究了异丙前列素对离体兔睫状动脉的影响。
在显微镜观察下，从兔眼制备睫状动脉并安装在肌动描记系统中。使用等长张力记录在体外研究异丙前列素对离体兔睫状动脉的影响。
外源性应用PG F(2α)可引起兔睫状动脉收缩，但异丙前列素无此作用。用高钾（o）溶液预收缩后，异丙前列素引起剂量依赖性舒张。该舒张不受10μM/L N(G)-硝基-L-精氨酸甲酯（L-NAME）、1μM/L 8-37降钙素基因相关肽（8-37 CGRP）或10μM/L吲哚美辛的阻断。此外，异丙前列素即使在无内皮的制剂中也能诱导舒张。地尔硫䓬诱导的舒张在高钾（o）溶液预收缩的肌肉中比在10μM/L组胺预收缩的肌肉中更大。另一方面，异丙前列素在两种药物预收缩的肌肉中诱导的舒张幅度相似。
这些结果表明异丙前列素直接作用于兔睫状动脉使其舒张。该舒张不依赖于内皮，也不是由内源性前列腺素、CGRP或一氧化氮引起的。此外，该舒张与钙（2+）拮抗剂引起的舒张不同。这种舒张的机制尚未确定。
