The effects of lowered extracellular sodium on gamma-aminobutyric acid (GABA)-induced currents of Muller (glial) cells of the skate retina.
The effects of lowered extracellular sodium on gamma-aminobutyric acid (GABA)-induced currents of Muller (glial) cells of the skate retina.
复制标题
细胞外钠浓度降低对鳐鱼视网膜 Muller（神经胶质）细胞的 γ-氨基丁酸 (GABA) 诱导电流的影响。
DOI：
10.1007/bf00735371
复制
发表时间：
1993
影响因子：
4
通讯作者：
Ripps,H
中科院分区：
文献类型：
--
作者：
Qian,H;Malchow,RP;Ripps,H
1. The effects of external sodium on GABA-induced chloride currents were examined with whole-cell voltage-clamp recordings obtained from enzymatically dissociated solitary Muller cells in culture. Our goal was to determine whether a sodium-dependent GABA uptake mechanism influences the GABAa-mediated responses of skate Muller cells. 2. At low concentrations of GABA (0.01 to 0.5 microM), removal of sodium from the external solution resulted in a marked increase in the ligand-gated currents mediated by activation of GABAa receptors. The enhancement by lowered sodium was greatest at hyperpolarizing potentials and decreased progressively as the cell was depolarized. 3. The reversal potential for the GABA-induced response was not significantly altered by the removal of sodium, suggesting that sodium ions did not directly contribute to the GABAa-mediated current. 4. Lowering external sodium had no effect on the currents induced by the GABAa-agonist muscimol, consistent with its much lower affinity for the GABA transport carrier. 5. Application of the GABA uptake blocker nipecotic acid also abolished the effects of lowered sodium. 6. These findings suggest that the effects of lowered external sodium resulted from a decrease in the uptake of GABA into the Muller cells, thus raising the effective concentration of GABA acting upon the GABAa receptors.
