EFFECTS OF EXTRACELLULAR CA++, K+, AND NA+ ON CONE AND RETINAL-PIGMENT EPITHELIUM RETINOMOTOR MOVEMENTS IN ISOLATED TELEOST RETINAS
EFFECTS OF EXTRACELLULAR CA++, K+, AND NA+ ON CONE AND RETINAL-PIGMENT EPITHELIUM RETINOMOTOR MOVEMENTS IN ISOLATED TELEOST RETINAS
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DOI：
10.1085/jgp.83.4.589
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发表时间：
1984-01-01
影响因子：
3.8
通讯作者：
BURNSIDE, B
中科院分区：
文献类型：
--
作者：
DEARRY, A;BURNSIDE, B
在离体培养的硬骨鱼视网膜上研究了细胞外离子组成的变化对视锥细胞和视网膜色素上皮细胞（RPE）视网膜运动的影响。在体内，硬骨鱼视锥细胞的肌样部分在光照下收缩，在黑暗中伸长：RPE色素在光照下分散，在黑暗中聚集。在体外，如果培养基中含有≥ 50%的葡萄糖，则在恒定黑暗中培养的暗适应（DA）视网膜的视锥自发地收缩到它们的光适应（LA）位置。10-3 M Cao 2+。DA视锥细胞在含有≤10-6 M Cao 2+。低[Ca ~（2+）]o（10 ~（-5）~ 10 ~（-7）M）也可使黑暗诱导视锥细胞伸长和RPE色素聚集。即使在没有Cao ~（2+）存在的情况下，光也能引起视锥细胞收缩，但当[Ca ~（2+）]o < 10 ~（-3）M时，收缩程度降低。因此，完全收缩似乎需要外部Ca 2+的存在。高[K+]o（≥27 mM）抑制光诱导和光非依赖性Ca 2+诱导的视锥收缩。低[Na+]o（3.5 mM），在≤10-6 M Ca 2+没有模仿光发病诱导锥收缩在黑暗中。高[K+]o也促进光下培养的LA视网膜暗适应性视锥和RPE运动。在高[K+]o中获得的所有结果与DA或LA视网膜暴露于升高细胞质cAMP含量的治疗时观察到的结果相似。
The effects of changes in extracellular ionic composition on cone and retinal pigment epithelium (RPE) retinomotor movements was studied in cultured isolated teleost retinas. In vivo, the myoid portion of teleost cones contracts in the light and elongates in the dark: RPE pigment disperses in the light and aggregates in the dark. In vitro, cones of dark-adapted (DA) retinas cultured in constant darkness contracted spontaneously to their light-adapted (LA) positions if the culture medium contained .gtoreq. 10-3 M Cao2+. DA cones retained their long DA positions in a medium containing .ltoreq. 10-6 M Cao2+. Low [Ca2+]o (10-5-10-7 M) also permitted darkness to induce cone elongation and RPE pigment aggregation. Light produced cone contraction even in the absence of Cao++, but the extent of contraction was reduced if [Ca2+]o was < 10-3 M. Thus, full contraction appeared to require the presence of external Ca2+. High [K+]o (.gtoreq. 27 mM) inhibited both light-induced and light-independent Ca2+-induced cone contraction. Low [Na+]o (3.5 mM) in the presence of .ltoreq. 10-6 M Cao2+ did not mimic light onset by inducing cone contraction in the dark. High [K+]o also promoted dark-adaptive cone and RPE movements in LA retinas cultured in the light. All results obtained in high [K+]o were similar to those observed when DA or LA retinas were exposed to treatments that elevate cytoplasmic cAMP content.