Miledi R, Parker I
Proc R Soc Lond B Biol Sci. 1981 May 22;212(1187):197-211. doi: 10.1098/rspb.1981.0034.
Transient changes in free intracellular Ca2+ concentration were monitored in the presynaptic terminal of the giant synapse of the squid, by means of the Ca2+-sensitive dye arsenazo III. Calibration experiments showed a linear relation between the amount of Ca2+ injected by iontophoresis into the terminal, and the peak size of the arsenazo light absorbance record. A light signal could be detected on tetanic stimulation of the presynaptic axon bathed in sea water containing 45 mM Ca2+. During a 1 s tetanus the light signal rose approximately linearly, even though transmitter release declined rapidly and the light signal subsequently declined with a half-time of 2-6 s. The Ca2+ transient elicited by single nerve impulses was recorded by signal averaging, and showed a time course very much slower than the duration of transmitter release.
借助对Ca2+敏感的染料偶氮胂III，监测了枪乌贼巨大突触突触前终末内游离Ca2+浓度的瞬时变化。校准实验表明，通过离子电泳注入终末的Ca2+量与偶氮胂吸光度记录的峰值大小之间呈线性关系。在浸于含45 mM Ca2+海水的突触前轴突受到强直刺激时，可检测到光信号。在1秒的强直刺激期间，光信号大致呈线性上升，尽管递质释放迅速下降，随后光信号以2 - 6秒的半衰期下降。通过信号平均记录了单个神经冲动引发的Ca2+瞬变，其时间进程比递质释放的持续时间慢得多。
