Changes of Ionic Flow through the Internal Limiting Membrane during the Visual Adaptation of Vertebrate Eye.
- Author:
Hyun Jung KIM
1
;
Suk Hyang WOO
;
You Young KIM
;
Hyuk JUNG
;
Si Yeol KIM
;
Eun Hwi PARK
Author Information
1. Department of Biochemistry, College of Natural Sciences, Kyungpook National University.
- Publication Type:Original Article
- Keywords:
Channel blocker;
Electroretinogram(ERG);
Internal limiting membrane(ILM);
Vitreous humor(VH)
- MeSH:
Absorption;
Hand;
Ions;
Light Signal Transduction;
Lighting;
Membranes*;
Metabolism;
Permeability;
Photoreceptor Cells, Vertebrate;
Rana catesbeiana;
Retina;
Vertebrates*;
Vitreous Body
- From:Journal of the Korean Ophthalmological Society
2000;41(7):1479-1492
- CountryRepublic of Korea
- Language:Korean
-
Abstract:
It already has been known that various ions were participated in phototransduction mechanism of the vertebrate photoreceptor during the visual adaptation. The vitreous humor(VH)contains certain amount of Na+, K+ and Ca++ as well. However, the roles of these ions are unknown except functioning of metabolic process. Our preliminary electroretinogram(ERG) experiments suggested that the permeability of these ions has light dependent activity during the light illumination. We have supported this suggestion more tangibly by trying out various experiments with bullfrog eyes as a reference of visual adaptation. The results are summarized as follows: 1)According to our atomic absorption spectroscopic measurements, the concentration of Na+, K+ and Ca++ in light adapted VH was higher than that of dark adapted VH. This result indicated that the light-dependention transport systems which affect the ionic movements might be in internal limiting membrane(ILM). 2)The amplitude of ERG b-wave was reduced by concentration decrement of Na+ and concentration increment of K+ respectively. On the other hand, the elimination of Ca++ within ringer solution resulted in b-wave amplitude increment. 3)Treatment of Na+ hannel blockers(TTX, STX)and K+ channel blockers(Ba++, Cd++, Cs+, 4-AP and TEA)in the vitreous humor side induced the increment and the decrement of b-wave response respectively. Taken together, these results suggest that the light dependent Na+ K+ channels exist in the ILM of vertebrate retina which participates visual adaptation.
