網膜電図に対する Ba イオンの影響

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We investigated effects of Ba^<2+> on the generation of the b-wave of the electroretinogram by separately exposing the receptor or the vitreous side of the retina to various concentrations of Ba^<2+> (0.01-2.0 mM). The amplitude of the b-wave was inversely proportional to the log concentration of Ba^<2+>, but Ba^<2+> applied to the vitreous side showed stronger inhibitory effect on the b-wave than that applied to the receptor side. When 0.05 mM Ba^<2+> was applied to the vitreous side, the slow falling phase of the b-wave was suppressed. Vitreal positive off response was observed by the application of Ba^<2+> to the receptor or the vitreous side. In the presence of Ba^<2+> on the receptor or the vitreous side, the threshold of the b-wave was elevated from -9.0 to -8.0 log unit intensity and the peak of the spectral response curve of the b-wave shifted to a longer wavelength. These results suggest that 0.05 mM Ba^<2+> might suppress neuronal activity as to generation of the b-wave subserved by the rod system and that Ba^<2+> applied to the receptor side might have different action site to the retina from that applied to the vitreous side. On exposing the vitreous side to 2.0 mM Ba^<2+> solution, the b-wave was remarkably suppressed and only the negative going response (P II response) was observed. This response declined in amplitude by the following application of 5.0 mM aspartate to the receptor side. The slow P II response was not observed. The peak of the spectral response curve of the 2.0 mM Ba^<2+>-induced P II response lay at 550 nm and shifted to 500 nm by the following application of 5.0 mM aspartate. These results suggest that the P II response isolated by 2.0 mM Ba^<2+> might consist of the fast P II response and the proximal P II component, the latter reflecting neuronal activity proximal to the photoreceptors subserved mainly by the cone system.
神戸大学の論文

網膜電図に対する Ba イオンの影響

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