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Abstract #6186 Published in IGR 2-2
Effects of isopropyl unoprostone on rabbit ciliary artery
Hayashi E; Yoshitomi T; Ishikawa H; Hayashi R; Shimizu KJapanese Journal of Ophthalmology 2000; 44: 214-220
PURPOSE: Isopropyl unoprostone (unoprostone), a prostaglandin F(2α) (PG F(2α))-related compound, is widely used in Japan for the treatment of glaucoma and is reported to have effects on the ocular circulation. To investigate the action of this drug, the authors studied the effect of unoprostone on the isolated rabbit ciliary artery. METHODS: 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. RESULTS: Exogenously applied PG F(2α) but not unoprostone evoked contraction in the rabbit ciliary artery. After precontraction with excess-(K)(o) solution, unoprostone evoked dose-dependent relaxation. The relaxation was not blocked by 10 mu M/L N(G)-nitro-L-arginine methylester (L-NAME), 1 mu M/L 8-37 calcitonin gene-related peptide (8-37 CGRP) or 10 mu M/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)(o) solution than that precontracted by 10 mu M/L histamine. On the other hand, unoprostone induced a similar amplitude of relaxation in muscles precontracted by either drug. CONCLUSIONS: 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 sup(2)+ antagonist. The mechanism for this relaxation has not yet been determined.
Dr. T. Yoshitomi, Department of Ophthalmology, Wakayama Medical College, 81 1-1 Kimiidera, Wakayama, 641-0012, Japan
Classification:
11.4 Prostaglandins (Part of: 11 Medical treatment)
