• The Korean Journal of Physiology and Pharmacology
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• v.16 no.3
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• pp.219-224
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• 2012

Understanding how the b-wave of the electroretinogram (ERG) is generated by full-field light stimulation is still a challenge in visual neuroscience. To understand more about the origin of the b-wave, we studied the contributions of gap junctions to the ERG b-wave. Many types of retinal neurons are connected to similar and different neighboring neurons through gap junctions. The photopic (cone-dominated) ERG, stimulated by a small light beam, was recorded from goldfish (Carassius auratus) using a corneal electrode. Data were obtained before and after intravitreal injection of agents into the eye under a photopic illumination level. Several agents were used to affect gap junctions, such as dopamine D1 and D2 receptor agonists and antagonists, a nitric oxide (NO) donor, a nitric oxide synthase (NOS) inhibitor, the gap junction blocker meclofenamic acid (MFA), and mixtures of these agents. The ERG b-waves, which were enhanced by MFA, sodium nitroprusside (SNP), SKF 38393, and sulpiride, remained following application of a further injection of a mixture with MFA. The ERG b-waves decreased following $N^G$-nitro-L-arginine methyl ester (L-NAME), SCH 23390, and quinpirole administration but were enhanced by further injection of a mixture with MFA. These results indicate that gap junction activity influences b-waves of the ERG related to NO and dopamine actions.

• Journal of Veterinary Clinics
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• v.37 no.3
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• pp.130-134
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• 2020

This study aimed to confirm the effects that the mobile phone has on Electroretinogram (ERG). The ERG responses of three groups of healthy dogs, five in each group, were studied. ERG test was performed consecutively before and after the mobile phone was carried out. For group A, music was played with the sound on; for group B, music was played but the sound off; and for group C, the phone was set on the airplane mode. In the presence of a mobile phone, the amplitudes of a- and b-wave were increased in all groups. The a- and b-wave amplitudes at the flash intensity of 3,000 mcd·s/㎡ were significantly increased in all groups (p < 0.05). Based on the results, it is recommended to conduct ERG test in the absence of a mobile phone for the accurate evaluation of the retinal function.

• Korean Journal of Clinical Laboratory Science
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• v.43 no.2
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• pp.33-42
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• 2011

Zinc plays a key role in genetic expression, cell division, and cell growth and is essential for the functions of more than 450 metalloenzyme. There are high concentrations of zinc in pigment epithelium in bullfrog eye. Zinc deficiency causes night blindness and abnormal dark adaptation. The purpose of this study was to identify ERG (electroretinogram) b-wave sensitivity during light and dark adaptation in bullfrog retina after zinc and zinc chelators treatment such as histidine and TSQ (N-(6-methoxy-8-qunolyl)-p-toluenesulfon amide). Especially, we focused whether histidine act as a zinc chelator in the Muller cell. The results of our study are summarized as follows: 1) Both zinc and histidine elevated ERG b-wave amplitude and threshold in Muller cells by accelerating rhodopsin regeneration time and increased a-peak absorbance during light adaptation. 2) TSQ reduced those by prolonging rhodopsin regeneration time and decrement of a-peak absorbance during light adaptation. 3) Zinc shortened rhodopsin regeneration time and prolonged a-peak absorbance. These results suggested that histidine may act as a zinc-mediated transporter in presynaptic Muller cell membrane rather than zinc chelator and acts as a GABA-receptor inhibitor which blocks $Cl^-$ influx to the postsynapse.

• Journal of Photoscience
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• v.7 no.4
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• pp.161-167
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• 2000

Temperature-dependent electroretinogram responses were investigated in the dark adapted bullfrog eyes within the physiological temperature range 0-40$\^{C}$. In hypothermic process(25→0→25$\^{C}$), the amplitude of b-and c-wave decreased with lowering the temperature again. Both b-wave amplitude and threshold responses were maximal around 15$\^{C}$ during the temperature increment. Upon warming to room temperature again (25$\^{C}$), the b-wave amplitude was approximately doubled as compared to that of control without temperature changes. During the hyperthermic process (25→40→25$\^{C}$), however, the responses decreased with warming, and the wave amplitude failed to recover by cooling to 25$\^{C}$ again. As describe above, the recoveries of ERG in both processes show the striking difference. The hypothermia induces the amplification of the b-wave, that is, enhances the retinal function with the temperature recovery toward room temperature. While the hypertherima produces the decrease of the b-wave even though recovered to room temperature, which indicates an irreversible retina. The morphological alteration is shown both hypothermic and hyperthermic process, such as an appearance of large vacuoles and degenerating outer segments, more intense in hyperthermia, similar to light induced damage.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.3
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• pp.229-235
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• 2013

Among several animal models of retinitis pigmentosa (RP), the more recently developed rd10 mouse with later onset and slower rate of retinal degeneration than rd1 mouse is a more suitable model for testing therapeutic modalities. We therefore investigated the time course of retinal degeneration in rd10 mice before adopting this model in our interventional studies. Electroretinogram (ERG) recordings were carried out in postnatal weeks (PW) 3~5 rd10 (n=23) and wild-type (wt) mice (n=26). We compared the amplitude and implicit time of the b-wave of ERG records from wt and rd10 mice. Our results showed that b-wave amplitudes in rd10 mice were significantly lower and the implicit time of b-waves in rd10 mice were also significantly slower than that in wt mice ($20{\sim}160{\mu}V$ vs. $350{\sim}480{\mu}V$; 55~75 ms vs. 100~150 ms: p<0.001) through PW3 to PW5. The most drastic changes in ERG amplitudes and latencies were observed during PW3 to PW4. In multichannel recording of rd10 retina in PW2 to PW4.5, we found no significant difference in mean spike frequency, but the frequency of power spectral peak of local field potential at PW3 and PW3.5 is significantly different among other age groups (p<0.05). Histologic examination of rd10 retinae showed significant decrease in thickness of the outer nuclear layer at PW3. TUNEL positive cells were most frequently observed at PW3. From these data, we confirm that in the rd10 mouse, the most precipitous retinal degeneration occurs between PW3~PW4 and that photoreceptor degeneration is complete by PW5.

• Journal of Photoscience
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• v.7 no.3
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• pp.115-121
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• 2000

Although there are high concentrations of zinc and taurine in ocular tissue, their exact role and correlation in the visual process are not clear. The purpose of present study was to clarity this point using electroretinogram (ERG) recording and spectrophotometer measurements before and after zinc and taurine treatment in bullfrog's eye. The optimal zinc concentration used in this study was 10$^{-2}$ M ZnCl$_2$120 ${mu}ell$/12$m\ell$ ringer solution while the optimal turine concentration was 10$^{-2}$ M taurine 12${mu}ell$/12$m\ell$ ringer solution. For the effects of zinc and taurine on the retinal function, the changes of ERG parameters (especially threshold and b-wave) and absorption spectra were observed before and after treatment. It is noteworthy that high concentrations of zinc and taurine present in the retinal pigment epithelium and the retina. Our results indicate that dark-adapted ERG threshold became elevated and the peak amplitude of b-wave was increased with zinc and taurine treatment. Furthermore there are some synergism effects between zinc and taurine as a result of co-treatment. In spectral scan, absorbance increment due to zinc and taurine treatment was shown over the whole range of spectral range (300-750 nm) with some differences in absorbance increment depending on the case of treatment. As the results of above we believe that zinc and taurine, which are abundant in the retinal pigment epithelium and the retina particularly, may be essential factors for visual process, have some synergism with each other and be required to improve the visual sensitivity during visual adaptation.

• Journal of Korean Ophthalmic Optics Society
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• v.12 no.1
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• pp.23-33
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• 2007

It has been reported high concentrations of zinc and taurine in ocular tissue, especially the retina-choroid, and the presence of physiological levels of zinc and taurine in these tissues seem essential for their normal function. In addition, several studies have reported temperature as another effector to the visual sensitivity. But, in spite of many studies, there are still remained many questions about their function and correlation in visual adaptation system. The purpose of present study was to clarify these points using electroretinogram(ERG) recording and absorption spectra scanning, before and after zinc and taurine treatments and hypothermic-effect in bullfrog(Rana catesbeiana) which is one of the poikilothermal animal. The optimal zinc concentration used in this study was determined $10^{-4}M$ while the optimal taurine concentration was 10-5 M, and temperature change for hypothermic-effect went through '$25^{\circ}C {\rightarrow}0^{\circ}C{\rightarrow}25^{\circ}C$'. In ERG recording, it is obtained that dark-adapted threshold became elevated and b-wave amplitudes was increased with zinc and taurine treatment and hypothermic-effect. In absorption spectra scanning, there is distinct absorbance increment over the whole spectral range(400~750 nm) after zinc and taurine treatment and hypothermic-effect. Furthermore there are some synergism effects between zinc and taurine as well as between zinc and hypothermic-effect as a result of co-treatment, respectively.

• Molecules and Cells
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• v.19 no.3
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• pp.382-390
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• 2005

Calcium-binding proteins are thought to play important roles in calcium buffering. The present study investigated the effects of ischemia and reperfusion on calbindin D28K, calretinin, and parvalbumin immunoreactivity in the ganglion cell layer of the rabbit. Rabbits were administered ischemic damage by increasing the intraocular pressure. After 60 and 90 min of ischemia, reperfusion (7 d) was allowed to occur. The b-wave of the electroretinogram (ERG) was reduced by more than 50% and almost 80% in retina given ischemia for 60 and 90 min, respectively. The oscillatory potential (OPs) wave was reduced approximately 50% at 60 min ischemia and 70% at 90 min ischemia. In both normal and ischemic-treated retina, calcium-binding protein immunoreactivity was seen in many cells in the ganglion cell layer. In eyes subjected to 60 min ischemia, there was a decrease of the density of calbindin D28K- (8.29%), calretinin- (14.44%), and parvalbumin- (26.83%) immunoreactive (IR) cells compared to the control retina. In eyes subjected to 90 min ischemia, there was a higher decrease of the density of calbindin D28K- (18.48%), calretinin- (33.59%), and parvalbumin- (54.26%) IR cells than at 60 min. Some calcium-binding protein-IR neurons, especially calretinin-IR neurons, showed aggregations that were abnormally packed together in retina subjected to ischemia for 90 min. The results show that calbindin D28K-, calretinin-, and parvalbumin-IR cells in the ganglion cell layer are susceptible to ischemic damage and reperfusion. The degree of reduction varied among different calcium-binding proteins and ischemic damage times. These results suggest that calbindin D28K-containing neurons are less susceptible to ischemic damage than calretinin- and parvalbumin-containing neurons in the ganglion cell layer of rabbit retina.