TY - JOUR
T1 - Dual electroretinogram/nitric oxide carbon fiber microelectrode for direct measurement of nitric oxide in the in vivo retina
AU - Guthrie, Micah J.
AU - Kang-Mieler, Jennifer J.
PY - 2014/3
Y1 - 2014/3
N2 - Nitric oxide (NO) plays an important physiological role in normal and pathological retinas. Intraretinal NO concentrations have not been directly measured due to lack of NO electrodes capable of determining their location in the retina. The microelectrodes described here allow recording of the intraretinal electroretinogram (ERG) and NO concentration from the same location, with ERGs used to determine retinal depth. Double-barreled electrodes were constructed with one barrel serving as a reference/voltage recording barrel and the other containing a Nafion-coated carbon fiber used to detect NO amperometrically. Nafion coating imparted a high selectivity for NO versus ascorbic acid (2000:1). In vivo rodent experiments demonstrated that the electrodes could record intraretinal ERGs and NO current with minimal retinal thickness deformation (9%), allowing for retinal NO depth profile measurements. Comparison of NO depth profiles under control conditions and under nitric oxide synthase (NOS) inhibition by 5 mM L-NG-Nitroarginine methyl ester (L-NAME) verified that the recorded current was attributable to NO. NO concentrations from control profiles (n = 4) were 2.37 ± 0.34 μM at the choroid and 1.12 ± 0.14 μM at the retinal surface. NO concentrations from L-NAME profiles (n = 4) were significantly lower at 0.83 ± 0.15 μM at the choroid (p = 0.006) and 0.27 ± 0.04 μM at the retinal surface (p = 0.001). Localized regions of increased NO (100-400 nM) were seen in the inner retina under control conditions but not after L-NAME. The dual ERG-NO electrode may be a valuable tool in evaluating the role of NO in normal and diseased retinas.
AB - Nitric oxide (NO) plays an important physiological role in normal and pathological retinas. Intraretinal NO concentrations have not been directly measured due to lack of NO electrodes capable of determining their location in the retina. The microelectrodes described here allow recording of the intraretinal electroretinogram (ERG) and NO concentration from the same location, with ERGs used to determine retinal depth. Double-barreled electrodes were constructed with one barrel serving as a reference/voltage recording barrel and the other containing a Nafion-coated carbon fiber used to detect NO amperometrically. Nafion coating imparted a high selectivity for NO versus ascorbic acid (2000:1). In vivo rodent experiments demonstrated that the electrodes could record intraretinal ERGs and NO current with minimal retinal thickness deformation (9%), allowing for retinal NO depth profile measurements. Comparison of NO depth profiles under control conditions and under nitric oxide synthase (NOS) inhibition by 5 mM L-NG-Nitroarginine methyl ester (L-NAME) verified that the recorded current was attributable to NO. NO concentrations from control profiles (n = 4) were 2.37 ± 0.34 μM at the choroid and 1.12 ± 0.14 μM at the retinal surface. NO concentrations from L-NAME profiles (n = 4) were significantly lower at 0.83 ± 0.15 μM at the choroid (p = 0.006) and 0.27 ± 0.04 μM at the retinal surface (p = 0.001). Localized regions of increased NO (100-400 nM) were seen in the inner retina under control conditions but not after L-NAME. The dual ERG-NO electrode may be a valuable tool in evaluating the role of NO in normal and diseased retinas.
KW - Amperometry
KW - electroretinography
KW - in vivo
KW - nitric oxide
KW - retina
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U2 - 10.1109/TBME.2013.2281541
DO - 10.1109/TBME.2013.2281541
M3 - Article
C2 - 24043366
AN - SCOPUS:84896852128
SN - 0018-9294
VL - 61
SP - 611
EP - 619
JO - IEEE Transactions on Biomedical Engineering
JF - IEEE Transactions on Biomedical Engineering
IS - 3
M1 - 6595558
ER -