Uptake of aspartic and glutamic acid by photoreceptors in goldfish retina.
Uptake of aspartic and glutamic acid by photoreceptors in goldfish retina.
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金鱼视网膜中的光感受器吸收天冬氨酸和谷氨酸。
DOI：
10.1073/pnas.78.11.7185
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发表时间：
1981
影响因子：
11.1
通讯作者：
Lam,DM
中科院分区：
文献类型：
--
作者：
Marc,RE;Lam,DM
用光镜放射自显影法研究了金鱼光感受器对酸性氨基酸的摄取。将分离的视网膜在含有微摩尔量的L-[3 H]天冬氨酸、L-[3 H]谷氨酸和D-[3 H]天冬氨酸的培养基中孵育。我们有四个主要的观察。(i)棒积累L-[3 H]谷氨酸具有高亲和力的运输系统;它们表现出谷氨酸-天冬氨酸选择性比为30：1。当在1-10 μ M L-[3 H]谷氨酸中孵育时，视杆细胞比视锥细胞标记得更密集。单位面积的视杆细胞膜比单位面积的视锥细胞膜转运谷氨酸的能力强30倍。(ii)红色敏感和绿色敏感视锥细胞显示L-[3 H]天冬氨酸、D-[3 H]天冬氨酸和L-[3 H]谷氨酸的积累，显然具有高亲和力，但几乎没有选择性。由于视杆细胞对天冬氨酸的摄取较差，因此红敏感和绿敏感视锥细胞可能优先标记L-[3 H]天冬氨酸或D-[3 H]天冬氨酸，（iii）蓝敏感视锥细胞显示除低亲和力转运外不摄取L-[3 H]天冬氨酸、D-[3 H]天冬氨酸或L-[3 H]谷氨酸。(iv)金鱼视网膜中的各种细胞类型可以清楚地区分谷氨酸和天冬氨酸，不像哺乳动物大脑中描述的酸性氨基酸运输系统。
The uptake of acidic amino acids by goldfish photoreceptors was investigated by light microscope autoradiography. Isolated retinas were incubated in media containing micromolar amounts of L-[3H]aspartate, L-[3H]glutamate, and D-[3H]aspartate. We have four major observations. (i) Rods accumulate L-[3H]glutamate with a high-affinity transport system; they exhibit a glutamate-to-aspartate selectivity ratio of 30:1. When incubated in 1-10 microM L-[3H]glutamate, rods label more densely than cones. A unit area of rod membrane transports glutamate 30 times better than a unit area of cone membrane. (ii) Red-sensitive and green-sensitive cones show accumulation of L-[3H]aspartate, D-[3H]aspartate, and L-[3H]glutamate, apparently with high affinity, but with little selectivity. Because rods have poor aspartate uptake, red-sensitive and green-sensitive cones may be preferentially labeled with L-[3H]aspartate or D-[3H]aspartate, (iii) Blue-sensitive cones show no uptake of L-[3H]aspartate, D-[3H]aspartate, or L-[3H]glutamate other than that attributable to low-affinity transport. (iv) Various cell types in the goldfish retina can clearly discriminate between glutamate and aspartate, unlike acidic amino acid transport systems described in mammalian brain.