Physiological properties of GABA_A receptors from acutely dissociated rat dentate granule cells

作     者：Kapur, J Haas, KF MacDonald, RL 

作者机构：Univ Michigan Med Ctr Dept Neurol Ann Arbor MI 48104 USA Univ Michigan Med Ctr Dept Physiol Ann Arbor MI 48104 USA 

出 版 物：《JOURNAL OF NEUROPHYSIOLOGY》 (神经生理学杂志)

年 卷 期：1999年第81卷第5期

页      面：2464-2471页

核心收录：

学科分类：0710[理学-生物学] 1001[医学-基础医学(可授医学、理学学位)] 07[理学] 071003[理学-生理学] 

基　　金：NINDS NIH HHS [KO2 NS-02081  KO8 NS-01748  R01 NS-33300] Funding Source: Medline 

主　　题：腺苷三磷酸/药理学 齿状回/细胞学 齿状回/药物作用 齿状回/代谢 导电性 电生理学 神经元/药物作用 神经元/代谢 大鼠 Sprague-Dawley 受体 GABA-A/药物作用 受体 GABA-A/生理学 γ氨基丁酸/药理学 动物 女(雌)性 男(雄)性 大鼠 

摘      要：Study of fast, GABA, receptor-mediated, inhibitory postsynaptic currents (TPSCs) in hippocampal dentate granule cells has suggested that properties of GABA(A) receptors influence the amplitude and time course of the IPSCs. This study describes the physiological properties of GABA(A) receptors present on hippocampal dentate granule cells-acutely isolated from 18- to 35-day-old rats. Rapid application of 1 mM GABA to outside-out macropatches excised from granule cells produced GABA(A) receptor currents with rapid rise time and biexponential decay of current after removal of GABA. After activation,: granule cell GABA(A) receptor currents desensitized incompletely. During a 400-ms application of 1 mM GABA(A) peak current only desensitized similar to 40%. In symmetrical chloride solutions there was no outward rectification of whole cell current. Activation rates and peak currents elicited by rapid application of GABA to macropatches were also similar at positive and negative holding potentials. However, deactivation of GABA(A) receptor currents was slower at positive holding potentials. When whole cell currents were recorded without ATP in the pipette, current run-down was not apparent for 30 min in 50% of neurons, but run-down appeared to start soon after access was established in the remaining neurons. When 2 mM ATP was included in the recording pipette no run-down was apparent in 30 min of recording. The efficacy and potency of GABA were lower in cells recorded with no ATP in the pipette and during run-down compared with those recorded with 2 mM ATP and no run-down.