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Abstract #3624 Published in IGR 4-2
Effects of latanoprost, prostaglandin F2α and nipradilol on isolated bovine ciliary muscle
Yoshitomi T; Yamaji K; Ishikawa H; Ohnishi YJapanese Journal of Ophthalmology 2002; 46: 401-405
PURPOSE: Ciliary muscle tone is considered to be an important factor for the control of uveoscleral outflow. In an attempt to clarify the functional roles of the ciliary muscle in uveoscleral outflow, the effects of latanoprost, prostaglandin (PG)f2α or nipradilol, all of which are known to increase uveoscleral outflow, were investigated, using bovine ciliary muscle. METHODS: The authors isolated longitudinal ciliary muscle from bovine eyes and investigated the effects of these three agtents on the mechanical properties of this muscle, using isometric tension recording methods. RESULTS: Latanoprost and PGF-2α evoked small but discrete contractions at a concentration of 0.1 μM, even during the sustained contraction evoked by 10 mM acetylcholine (ACh). However, nipradilol did not evoke any response at concentrations of up to 0.1 mM. None of these agents had an effect on the amplitude of the ciliary muscle twitch contraction evoked by electrical field stimulation. CONCLUSIONS: These findings indicate that these agents have no relaxant effect on isolated bovine ciliary muscle, even during the sustained contraction evoked by ACh. Furthermore, these agents had no effect on the contraction evoked by field stimulation, which indicated that the drugs have no presynaptic effects. These results are inconsistent with the hypothesis that drugs that increase uveoscleral outflow relax the ciliary muscle, with a consequent increase in uveoscleral outflow. Further investigation into the role of ciliary muscle contractility on uveoscleral outflow is warranted.
Dr. T. Yoshitomi, Department of Ophthalmology, Wakayama Medical University, 811-1 Kimiidera, Wakayama, Wakayama 641-0012, Japan
Classification:
11.3.4 Betablocker (Part of: 11 Medical treatment > 11.3 Adrenergic drugs)
11.4 Prostaglandins (Part of: 11 Medical treatment)
