In the present study, cytosolic calcium concentration changes were recorded in response to various forms of excitations, using the fluorescent calcium indicator dye OG-BAPTA1 together with the current or voltage clamp methods in stretch receptor neurons of crayfish. A single action potential evoked a rise in the resting calcium level in the axon and axonal hillock, whereas an impulse train or a large saturating current injection would be required to evoke an equivalent response in the dendrite region. Under voltage clamp conditions, amplitude differences between axon and dendrite responses vanished completely. The fast activation time and the modulation of the response by extracellular calcium concentration changes indicated that the evoked calcium transients might be mediated by calcium entry into the cytosol through a voltage-gated calcium channel. The decay of the responses was slow and sensitive to extracellular sodium and calcium concentrations as well as exposure to 1–10 mM NiCl₂ and 10–500 µM lanthanum. Thus, a sodium calcium exchanger and a calcium ATPase might be responsible for calcium extrusion from the cytosol. Present results indicate that the calcium indicator OG-BAPTA1 might be an efficient but indirect way of monitoring regional membrane potential differences in a single neuron.

中文翻译：

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快速钙瞬变转变单个感觉神经元的不同区域中神经活动的分布和传导。

在本研究中，使用荧光钙指示剂染料OG-BAPTA1以及电流或电压钳制方法在小龙虾的拉伸受体神经元中记录了响应于各种形式的激发的胞浆钙浓度变化。单个动作电位引起了轴突和轴突丘陵中静息钙水平的升高，而在树突区域需要一个脉冲序列或一个大的饱和电流注入才能引起等效的响应。在电压钳位条件下，轴突和枝晶响应之间的幅度差异完全消失。快速激活时间和细胞外钙浓度变化对反应的调节表明，诱发的钙瞬变可能是由钙通过电压门控钙通道进入细胞质介导的。反应的衰减很慢，并且对细胞外钠和钙的浓度以及暴露于1-10 mM NiCl敏感₂和10–500 µM镧。因此，钠钙交换剂和钙ATP酶可能负责从细胞质中挤出钙。目前的结果表明，钙指示剂OG-BAPTA1可能是监测单个神经元中区域膜电位差异的有效但间接方法。