Eder C, Heinemann U
Institut für Physiologie der Charité, Abt. Neurophysiologie, Humboldt Universität zu Berlin, Tucholsky Strasse 2, D-10117 Berlin, Germany.
Pflugers Arch. 1996 Aug;432(4):637-43. doi: 10.1007/s004240050180.
Using the whole-cell configuration of the patch-clamp technique, outward K+ currents were recorded from acutely isolated stellate cells from superficial layers, and pyramidal cells from deep layers, of the entorhinal cortex of juvenile rats. In both cell types a fast transient and a slowly inactivating outward K+ current were obtained. Whereas the fast transient current (IA) activated at potentials beyond -50 mV, the activation threshold of the slowly inactivating current (IK) was measured at -40 mV in stellate and pyramidal cells. In stellate cells a half-maximal inactivation was estimated for IA at -80.4 mV and for IK at -74.6 mV, and in pyramidal cells at -81.1 mV and -71.8 mV, respectively. IK of both cell types were reduced by tetraethylammonium (TEA) in a concentration-dependent manner. IC50 values were 0.8 mM TEA for stellate cells and 1.1 mM TEA for pyramidal cells. Superfusion of 4-aminopyridine resulted in a reduction of the amplitudes of IA and IK as well as in an acceleration of the inactivation time constants of IA. Extracellularly applied dendrotoxin did not have any effect on entorhinal cortex K+ currents. In summary, kinetic and pharmacological properties of IA as well as of IK are rather similar in superficial-layer stellate and deep-layer pyramidal cells acutely isolated from the entorhinal cortex of juvenile rats.
采用膜片钳技术的全细胞模式，记录了幼年大鼠内嗅皮层浅层急性分离的星状细胞和深层锥体细胞的外向钾电流。在这两种细胞类型中，均获得了快速瞬态外向钾电流和缓慢失活外向钾电流。快速瞬态电流（IA）在超过 -50 mV 的电位时激活，而缓慢失活电流（IK）在星状细胞和锥体细胞中的激活阈值为 -40 mV。在星状细胞中，IA 的半最大失活电位估计为 -80.4 mV，IK 为 -74.6 mV；在锥体细胞中，IA 和 IK 的半最大失活电位分别为 -81.1 mV 和 -71.8 mV。两种细胞类型的 IK 均被四乙铵（TEA）以浓度依赖性方式降低。星状细胞的 IK50 值为 0.8 mM TEA，锥体细胞为 1.1 mM TEA。用 4-氨基吡啶灌流导致 IA 和 IK 的幅度降低，以及 IA 的失活时间常数加快。细胞外应用树突毒素对内嗅皮层钾电流没有任何影响。总之，从幼年大鼠内嗅皮层急性分离的浅层星状细胞和深层锥体细胞中，IA 和 IK 的动力学和药理学特性相当相似。
