O'Dell T J
Neuroscience Graduate Program, University of Texas Medical Branch, Galveston 77550.
Brain Res. 1989 Jan 16;477(1-2):118-25. doi: 10.1016/0006-8993(89)91399-1.
Excitatory amino acid-induced currents were examined in voltage-clamped rod horizontal cells dissociated from the catfish retina. The cells responded to glutamate (GLU) and the GLU analogues kainate (KA), quisqualate (QA), and alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), while N-methyl-D-aspartate (NMDA) produced inconsistent responses. Of the effective agonists, only KA produced large, concentration-dependent current responses. While QA, AMPA, GLU, and NMDA were poor agonists, these compounds were able to block rod horizontal cell responses to KA. The rank order potency for this inhibition was: QA greater than AMPA greater than or equal to L-GLU much greater than D-GLU = NMDA. Several excitatory amino acid receptor antagonists were also able to inhibit rod horizontal cell responses to KA. The rank order potency for the inhibition by the compounds tested was: kynurenate greater than cis-piperidine-dicarboxylic acid much greater than D,L-alpha-amino-adipate. Comparison of the potency of several ligands to inhibit rod and cone horizontal cell responses to KA suggested similarities in the KA binding sites of both cell types.
在从鲶鱼视网膜分离的电压钳制的视杆水平细胞中检测了兴奋性氨基酸诱导的电流。这些细胞对谷氨酸（GLU）以及GLU类似物红藻氨酸（KA）、quisqualate（QA）和α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）有反应，而N-甲基-D-天冬氨酸（NMDA）产生的反应不一致。在有效的激动剂中，只有KA产生大的、浓度依赖性的电流反应。虽然QA、AMPA、GLU和NMDA是较弱的激动剂，但这些化合物能够阻断视杆水平细胞对KA的反应。这种抑制的效价顺序为：QA＞AMPA≥L-GLU＞＞D-GLU = NMDA。几种兴奋性氨基酸受体拮抗剂也能够抑制视杆水平细胞对KA的反应。所测试化合物的抑制效价顺序为：犬尿氨酸＞顺式哌啶二羧酸＞＞D，L-α-氨基己二酸。比较几种配体抑制视杆和视锥水平细胞对KA反应的效价表明，两种细胞类型的KA结合位点具有相似性。
