Hideki Chuman1, Takako Sugimoto2, Nobuhisa Nao-I2. 1. Department of Ophthalmology, Faculty of Medicine, University of Miyazaki, 5200 Kihara Kiyotake, Miyazaki City, Miyazaki Prefecture, 889-1692, Japan. hchuman@med.miyazaki-u.ac.jp. 2. Department of Ophthalmology, Faculty of Medicine, University of Miyazaki, 5200 Kihara Kiyotake, Miyazaki City, Miyazaki Prefecture, 889-1692, Japan.
Abstract
PURPOSE: This study aimed to clarify the vasodilatory effect of L-arginine on isolated rabbit and human posterior ciliary arteries (PCAs) and to investigate changes in optic disc blood flow after an infusion of L-arginine in vivo. METHODS: Vascular ring segments were mounted on a double myograph system. After obtaining maximal contraction following administration of high-K solution, L-arginine was administrated. Six volunteers received an intravenous drip infusion of 100 ml of L-arginine or saline. Changes in optic disc blood flow were measured by laser speckle flowgraphy. RESULTS: L-arginine relaxed high-K solution-induced contracted rabbit PCAs. Carboxy-PTIO (nitric oxide scavenger) and L-NAME (nitric oxide synthase inhibitor) inhibited L-arginine-induced relaxation in rabbit PCAs. After removal of the endothelium of the rabbit PCAs, L-arginine still relaxed rabbit PCAs. L-arginine relaxed human PCAs, despite the lack of nitric oxide production. In the L-arginine infusion group, the mean blur rate was significantly greater than that of the control group in vivo. CONCLUSION: L-arginine has both nitric oxide-dependent and independent vasodilatory effect on high K- induced contractions in isolated rabbit and human PCAs. L-arginine increased optic disc blood flow in vivo.
PURPOSE: This study aimed to clarify the vasodilatory effect of L-arginine on isolated rabbit and human posterior ciliary arteries (PCAs) and to investigate changes in optic disc blood flow after an infusion of L-arginine in vivo. METHODS: Vascular ring segments were mounted on a double myograph system. After obtaining maximal contraction following administration of high-K solution, L-arginine was administrated. Six volunteers received an intravenous drip infusion of 100 ml of L-arginine or saline. Changes in optic disc blood flow were measured by laser speckle flowgraphy. RESULTS:L-arginine relaxed high-K solution-induced contracted rabbit PCAs. Carboxy-PTIO (nitric oxide scavenger) and L-NAME (nitric oxide synthase inhibitor) inhibited L-arginine-induced relaxation in rabbit PCAs. After removal of the endothelium of the rabbit PCAs, L-arginine still relaxed rabbit PCAs. L-arginine relaxed human PCAs, despite the lack of nitric oxide production. In the L-arginine infusion group, the mean blur rate was significantly greater than that of the control group in vivo. CONCLUSION:L-arginine has both nitric oxide-dependent and independent vasodilatory effect on high K- induced contractions in isolated rabbit and human PCAs. L-arginine increased optic disc blood flow in vivo.
Authors: Stephanie J Loomis; Jae H Kang; Robert N Weinreb; Brian L Yaspan; Jessica N Cooke Bailey; Douglas Gaasterland; Terry Gaasterland; Richard K Lee; Paul R Lichter; Donald L Budenz; Yutao Liu; Tony Realini; David S Friedman; Catherine A McCarty; Sayoko E Moroi; Lana Olson; Joel S Schuman; Kuldev Singh; Douglas Vollrath; Gadi Wollstein; Donald J Zack; Murray Brilliant; Arthur J Sit; William G Christen; John Fingert; Peter Kraft; Kang Zhang; R Rand Allingham; Margaret A Pericak-Vance; Julia E Richards; Michael A Hauser; Jonathan L Haines; Louis R Pasquale; Janey L Wiggs Journal: Ophthalmology Date: 2013-10-25 Impact factor: 12.079
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