Vasodilatory effect of L-arginine on isolated rabbit and human posterior ciliary arteries in vitro and increased optic disc blood flow in vivo.
キーワード
概要
OBJECTIVE
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.
CONCLUSIONS
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.
