Bolsover S R, Spector I
J Neurosci. 1986 Jul;6(7):1934-40. doi: 10.1523/JNEUROSCI.06-07-01934.1986.
Voltage-gated changes in cytosolic free calcium ion concentration were measured in single, differentiated cells of mouse neuroblastoma clone N1E-115 using the calcium-sensitive dye arsenazo III (AIII). In cells bathed in normal medium containing 10 mM calcium, the changes in AIII absorbance during a single action potential indicated an increase of 1.4 nM in cytosolic calcium. When 10 mM tetraethylammonium (TEA) was added to the bath, the action potential became prolonged and the change in cytosolic calcium increased to 3.9 nM. Under these conditions, repetitive stimulation at 0.5 Hz or faster caused a gradual decline in the amplitude and duration of the action potential and a gradual decline of the change in cytosolic calcium associated with each action potential. The amplitude of the prolonged after-hyperpolarization (AHP) that follows the action potential was found to reflect the magnitude of the change in cytosolic calcium. An action potential elicited in the cell soma caused an increase in cytosolic calcium in the soma, neurite, and growth cone regions of a single cell, indicating that the membrane of all three regions possesses voltage-gated calcium channels. Estimation of calcium flux per unit area of membrane suggests a distinct topographical organization of calcium channels. Calcium channel densities in the growth cone and cell soma regions are similar and significantly higher than that in the neurite.
使用钙敏染料偶氮胂III（AIII），在小鼠神经母细胞瘤克隆N1E-115的单个分化细胞中测量了胞质游离钙离子浓度的电压门控变化。在含有10 mM钙的正常培养基中培养的细胞中，单个动作电位期间AIII吸光度的变化表明胞质钙增加了1.4 nM。当向浴液中加入10 mM四乙铵（TEA）时，动作电位延长，胞质钙变化增加到3.9 nM。在这些条件下，以0.5 Hz或更快的频率重复刺激会导致动作电位的幅度和持续时间逐渐下降，以及与每个动作电位相关的胞质钙变化逐渐下降。发现动作电位之后的延长后超极化（AHP）的幅度反映了胞质钙变化的大小。在细胞体中引发的动作电位会导致单个细胞的细胞体、神经突和生长锥区域的胞质钙增加，这表明这三个区域的膜都具有电压门控钙通道。对单位膜面积钙通量的估计表明钙通道具有独特的拓扑结构。生长锥和细胞体区域的钙通道密度相似，且显著高于神经突中的钙通道密度。
