TY - JOUR
T1 - The effect of systemic nitric oxide-synthase inhibition on ocular fundus pulsations in man
AU - Schmetterer, Leopold
AU - Krejcy, Kurt
AU - Kastner, Johannes
AU - Wolzt, Michael
AU - Gouya, Ghazaleh
AU - Findl, Oliver
AU - Lexer, Franz
AU - Breiteneder, Helene
AU - Fercher, Adolf Friedrich
AU - Eichler, Hans Georg
PY - 1997/3
Y1 - 1997/3
N2 - There is experimental evidence that endothelium derived nitric oxide is involved in the regulation of ocular vascular tone. The purpose of this study was to investigate the effects of NO-synthase inhibition by N-monomethyl-L-arginine (L-NMMA) on ocular fundus pulsations in young healthy volunteers. Three milligrams per kilograms L-NMMA were administered i.v. over 5 minutes. Protocol 1: Measurements of blood pressure, pulse rate, fundus pulsation amplitude, NO-exhalation, and cardiac output were performed at baseline and 10, 30, 60, 90, 150, and 300 minutes after L-NMMA infusion (n = 8). Fundus pulsation amplitude, which has been shown to estimate the pulsatile component of the choroidal blood flow, was recorded with a recently developed laser interferometer. Protocol 2: Measurements of blood pressure, pulse rate, fundus pulsation amplitude, NO-exhalation, and blood flow velocity in the ophthalmic artery were performed in a randomized, placebo controlled cross over study (n = 10). Ten minutes after L-NMMA administration fundus pulsation amplitude decreased by 23 ± 2% (protocol 1) and 19 ± 1% (protocol 2, P < 0.01 each), cardiac output by 12 ± 2% (P < 0.01), and exhaled NO by 55 ± 6% (protocol 1) and 41 ± 6% (protocol 2, P < 0.01 each). All parameters returned to baseline values within the 300 minutes observation period, with a faster recovery of fundus pulsation amplitude than of cardiac output and exhaled NO. Blood pressure, pulse rate, and ophthalmic artery blood flow velocity showed only minor changes during and after administration of L-NMMA. Our results suggest that systemic NO-synthase inhibition reduces pulsatile choroidal and most likely total choroidal blood flow in humans. The recovery of vascular tone in choroidal vessels seems to be different from the cardiovascular response. Our findings indicate that reduced fundus pulsations after L-NMMA are caused by systemic factors as well as by local reactions of the choroidal vasculature.
AB - There is experimental evidence that endothelium derived nitric oxide is involved in the regulation of ocular vascular tone. The purpose of this study was to investigate the effects of NO-synthase inhibition by N-monomethyl-L-arginine (L-NMMA) on ocular fundus pulsations in young healthy volunteers. Three milligrams per kilograms L-NMMA were administered i.v. over 5 minutes. Protocol 1: Measurements of blood pressure, pulse rate, fundus pulsation amplitude, NO-exhalation, and cardiac output were performed at baseline and 10, 30, 60, 90, 150, and 300 minutes after L-NMMA infusion (n = 8). Fundus pulsation amplitude, which has been shown to estimate the pulsatile component of the choroidal blood flow, was recorded with a recently developed laser interferometer. Protocol 2: Measurements of blood pressure, pulse rate, fundus pulsation amplitude, NO-exhalation, and blood flow velocity in the ophthalmic artery were performed in a randomized, placebo controlled cross over study (n = 10). Ten minutes after L-NMMA administration fundus pulsation amplitude decreased by 23 ± 2% (protocol 1) and 19 ± 1% (protocol 2, P < 0.01 each), cardiac output by 12 ± 2% (P < 0.01), and exhaled NO by 55 ± 6% (protocol 1) and 41 ± 6% (protocol 2, P < 0.01 each). All parameters returned to baseline values within the 300 minutes observation period, with a faster recovery of fundus pulsation amplitude than of cardiac output and exhaled NO. Blood pressure, pulse rate, and ophthalmic artery blood flow velocity showed only minor changes during and after administration of L-NMMA. Our results suggest that systemic NO-synthase inhibition reduces pulsatile choroidal and most likely total choroidal blood flow in humans. The recovery of vascular tone in choroidal vessels seems to be different from the cardiovascular response. Our findings indicate that reduced fundus pulsations after L-NMMA are caused by systemic factors as well as by local reactions of the choroidal vasculature.
KW - Choroidal circulation
KW - Fundus pulsations
KW - Human
KW - Nitric oxide
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U2 - 10.1006/exer.1996.0213
DO - 10.1006/exer.1996.0213
M3 - Article
C2 - 9196381
AN - SCOPUS:0031105324
SN - 0014-4835
VL - 64
SP - 305
EP - 312
JO - Experimental Eye Research
JF - Experimental Eye Research
IS - 3
ER -