MEMBRANE-PROPERTIES OF SOLITARY HORIZONTAL CELLS ISOLATED FROM GOLDFISH RETINA
MEMBRANE-PROPERTIES OF SOLITARY HORIZONTAL CELLS ISOLATED FROM GOLDFISH RETINA
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DOI：
10.1113/jphysiol.1981.sp013976
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发表时间：
1981-01-01
影响因子：
5.5
通讯作者：
TACHIBANA, M
中科院分区：
文献类型：
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作者：
TACHIBANA, M
用木瓜蛋白酶分离成年金鱼视网膜，获得孤立的水平细胞。这些细胞在形态学上被鉴定，并且可以在培养物中保持一周以上。用微电极穿透的孤立水平细胞在正常溶液中的静息电位约为-75 mV。当外界K+浓度改变时，膜电位随能斯特方程计算的EK变化。所有测试的孤立水平细胞都表现出对超阈值去极化电流脉冲的动作电位。动作电位的过冲约为+20 mV，平台电位持续数秒。由于以下原因，动作电位似乎是钙依赖性的：TTX [河豚毒素]或低[Na+]不影响动作电位，Sr 2+、Ba 2+或高[Ca 2 +]增强动作电位，而Co 2+或高[Mg 2 +]阻断动作电位。K+的作用是通过增加的持续时间和幅度的动作电位上的应用程序的四乙铵。通过施加恒定电流脉冲测量的稳态电流-电压（I-V）曲线为S形（横坐标为电流），并且由向内和向外整流区以及它们之间的过渡区组成。在体内报告了类似的非线性I-V关系。过渡区的特点是突然的电位跳跃和滞后，表明存在负电阻。这种电位跳跃似乎不是由上述Ca-电导机制产生的，因为在Co2+存在下观察到类似的跳跃。
Solitary horizontal cells were obtained by dissociating the adult goldfish retina using the enzyme papain. The cells were identified on morphological grounds and could be kept in culture for over a week. Solitary horizontal cells, penetrated with microelectrodes, had resting potentials of about -75 mV in normal solution. When external K+ concentration was changed, the membrane potential varied with EK calculated from the Nernst equation. All solitary horizontal cells tested showed an action potential in response to superthreshold depolarizing current pulses. The action potential had an overshoot of about +20 mV and a plateau potential lasting for several seconds. The action potential appeared to be Ca-dependent for the following reasons: TTX [tetrodotoxin] or low [Na+] did not affect the action potential, Sr2+, Ba2+ or high [Ca2+] enhanced the action potential, while Co2+ or high [Mg2+] blocked it. No regenerative activity was observed in horizontal cells in the retina but it is possible that the regenerative mechanism is suppressed normally. A role for K+ was indicated by an increase in the duration and amplitude of the action potential on the application of tetraethylammonium. The steady-state current-voltage (I-V) curve, measured by applying constant current pulses, was S-shaped (current on the abscissa) and composed of inward- and outward-going rectifying regions and a transitional region between them. A similar non-linear I-V relationship was reported in vivo. The transitional region was characterized by a sudden potential jump and hysteresis, suggesting the presence of a negative resistance. This potential jump appeared not to be produced by the Ca-conductance mechanism mentioned above, since similar jumps were observed in the presence of Co2+.