Zona C, Avoli M
Dipartimento di Medicina Sperimentale e Scienze Biochimiche, Università di Roma Tor Vergata, Rome, Italy.
Neurosci Lett. 1989 Jul 31;102(2-3):223-8. doi: 10.1016/0304-3940(89)90082-7.
Rat neocortical neurons in cell culture were studied with the patch-clamp technique in order to determine the properties of a large-conductance K+ channel in excised inside-out patches. In the presence of a physiological ionic gradient for K+ across the patch membrane ([K+]i = 120 mM; [K+]o = 3 mM), outward channel activity was detected when the patches were brought to membrane potential values less negative than -30 mV. Depolarization of the membrane increased the magnitude of the current. The I-V relationship displayed rectification at negative membrane potentials. When the I-V curve was differentiated the slope conductance calculated at 0 mV membrane potential was 120 pS. The single-channel permeability was 5.2 x 10(-13) cm/s and the current flow through the open K+ channel could be modeled using the constant-field electrodiffusion theory. K+ channel opening was not observed following removal of Ca2+ from the intracellular surface of the membrane. Our experiments indicate that, as in other cell types, rat neocortical neurons in culture exhibit a large-conductance K+ channel which is activated by Ca2+ acting on the cytoplasmic surface.
为了确定在膜片钳技术下分离的内面向外膜片中的大电导钾通道的特性，对培养的大鼠新皮质神经元进行了研究。在膜片两侧存在生理钾离子梯度（[K⁺]i = 120 mM；[K⁺]o = 3 mM）的情况下，当膜片的膜电位低于-30 mV时，检测到外向通道活性。膜去极化增加了电流幅度。I-V关系在负膜电位时表现出整流特性。当对I-V曲线进行微分时，在膜电位为0 mV时计算出的斜率电导为120 pS。单通道通透性为5.2×10⁻¹³ cm/s，通过开放钾通道的电流可以用恒定场电扩散理论进行模拟。从膜的细胞内表面去除Ca²⁺后未观察到钾通道开放。我们的实验表明，与其他细胞类型一样，培养的大鼠新皮质神经元表现出一种大电导钾通道，该通道由作用于细胞质表面的Ca²⁺激活。
