Hiroi K, Yamamoto F, Honda Y
Department of Ophthalmology, Faculty of Medicine, Kyoto University, Japan.
Invest Ophthalmol Vis Sci. 1994 Oct;35(11):3957-61.
Systemic hypercapnia alters the intraretinal pH and metabolism and profoundly affects the vitreal electroretinogram (ERG). Using intraretinal K(+)-selective microelectrodes (ISMs), the authors examined the effects of systemic hypercapnia on ERG in the intact cat eye in vivo.
Double-barreled K(+)-ISMs were used to record intraretinal, light-evoked [K+]o decrease, intraretinal ERG, vitreal ERG, and standing potential (SP) in the dark-adapted retina. Hypercapnia was induced by adding CO2 to the inhaled mixture of gas (without significant hypoxia).
The standing potential was elevated, and the vitreal ERG c-wave increased in amplitude whereas the b-wave decreased during hypercapnia. Intraretinal recordings showed that the amplitudes of slow PIII and the transepithelial (TEP) c-wave decreased. The slow PIII decreased more than the TEP c-wave. The light-evoked [K+]o decrease also was reduced, but no change was noted in the subretinal [K+]o.
The neural retina was more sensitive than the retinal pigment epithelium to the intraretinal acidification caused by systemic hypercapnia. However, the change in the SP and b-wave suggested complicated effects other than acidosis.
全身性高碳酸血症会改变视网膜内的pH值和代谢，并深刻影响玻璃体视网膜电图（ERG）。作者使用视网膜内钾离子选择性微电极（ISMs），在活体完整猫眼中研究了全身性高碳酸血症对ERG的影响。
使用双管钾离子ISMs记录暗适应视网膜中的视网膜内光诱发的[K+]o降低、视网膜内ERG、玻璃体ERG和静息电位（SP）。通过向吸入的气体混合物中添加二氧化碳（无明显低氧）诱导高碳酸血症。
在高碳酸血症期间，静息电位升高，玻璃体ERG的c波振幅增加，而b波减小。视网膜内记录显示，慢PIII和跨上皮（TEP）c波的振幅降低。慢PIII的降低幅度大于TEP c波。光诱发的[K+]o降低也减少，但视网膜下[K+]o无变化。
神经视网膜比视网膜色素上皮对全身性高碳酸血症引起的视网膜内酸化更敏感。然而，SP和b波的变化表明除酸中毒外还有复杂的影响。
