Macro- and microscopic analysis of glycine-gated response in isolated CNS neurons.

在急性分离的幼年和成年大鼠下丘脑腹内侧部(VMH)神经元上，用“浓度钳”技术研究了甘氨酸诱发电流的药理特性和动力学。甘氨酸诱导的电流在氯离子平衡电位(E&lt；Cl&gt；)处发生翻转，胞外氯离子浓度变化10倍导致甘氨酸翻转电位发生53 mV的漂移。甘氨酸诱导的氯离子电流呈浓度依赖性增加，在Hill系数为1.8时，K_d为9×10~(-5)&gt；M。甘氨酸诱导的电导在膜电位大于-50 mV时表现出明显的电压依赖性，当超极化超过-110 mV时达到稳态值。甘氨酸诱导的反应的激活和失活阶段均由双指数函数…描述使用的浓度越高，离子越多(分别为快成分和慢成分)。四个时间常数均随甘氨酸浓度的增加而减小。士的宁和印防己毒素对甘氨酸反应的阻断是非竞争性的。士的宁选择性地拮抗士的宁，但不受荷包牡丹碱或牛磺酸拮抗剂TAG的影响，提示α-氨基酸和β-氨基酸激活相同的甘氨酸受体。有机钙阻滞剂对VMH神经元低阈值(T型)钙通道的药理作用不同于外周神经节细胞和培养神经元。用浓度钳技术研究了GABA对大鼠浦肯野细胞氯离子电流的影响。GABA受体的药理性质与以往报道的其他制剂基本相似。在分离的孤束核神经元中，甘氨酸启动NMDA受体的激活，而不是甘氨酸阻止细胞中NMDA受体的失敏。较少

Pharmacological properties and kinetics of glycine-induced currents were investigated in single ventromedial hypothalamic (VMH) neurons acutely isolated from young and adult rats by the use of a 'concentration-clamp' technique, which allows both internal perfusion and rapid application of an external solution under single-electrode voltage-clamp. The glycine-induced current reversed at the Cl^- equilibrium potential (E_<Cl>), and a ten-fold change of extracellular Cl^- concentration resulted in a 53 mV shift of the glycine reversal potential. Glycine-induced Cl^- currents increased sigmoidally in a concentration-dependent manner with a K_d of 9 x 10^<-5> M at the Hill coefficient of 1.8. The glycine-induced conductance exhibited a striking voltage dependency at membrane potentials more negative than -50 mV and reached a steady state value when hyperpolarized beyond -110 mV. Both the activation and inactivation phases of glycine-induced response are described by double exponential funct … More ions (fast and slow components, respectively) with the concentrations used. All four time constants decreased with increasing glycine concentration. The blockade of the glycine response by strychnine and picrotoxin was noncompetitive. The responses to individual alpha- and (bata-amino acids were selectively antagonized by strychnine, but were not affected by bicuculline or a taurine antagonist, TAG, suggesting that alpha-and beta-amino acids activate the same glycine receptor. The pharmacological properties of low-threshold (T-type) Ca channels of VMH neurons for organic Ca blockers differed from those of peripheral ganglion cells and cultured neurons. The GABA-induced Cl^- current in rat isolated Purkinje cells was also investigated by concentration-clamp technique. The pharmacological property of GABA receptor was basically similar to that previously reported in other preparations. In isolated nucleus tructus solitarii neurons, glycine initiates the activation of NMDA receptors rather than that glycine prevents the desensitivation at NMDA receptors in the cells. Less