Chabbert C, Geleoc G, Lehouelleur J, Sans A
Laboratoire de Neurophysiologie sensorielle et cellulaire, Université de Montpellier II, U254 INSERM, France.
Pflugers Arch. 1994 May;427(1-2):162-8. doi: 10.1007/BF00585956.
The variations of intracellular free calcium concentration ([Ca2+]i) were recorded on-line from guinea-pig isolated vestibular sensory cells using a fura-2 fast fluorescent photometry system, during mechanical displacements of the hair bundle. Repetitive displacements of the hair bundle towards the kinocilium (positive stimulation 7 degrees, 300 ms, 2Hz for 10 s), revealed [Ca2+]i variations detectable only in the cuticular plate. [Ca2+]i increased from 105 to 145 nM. Single mechanical displacements of the hair bundle (7 degrees, 200 ms, 0.5 Hz) evoked increases of [Ca2+]i from 50 +/- 23 nM to 139 +/- 79 (n = 12). In the opposite direction, the mechanical stimulations (8 degrees, 400 ms, 0.5 Hz) evoked a decrease of [Ca2+]i from 68 +/- 17 nM to 37 +/- 12 nM (n = 8). The variations of [Ca2+]i detected in the cuticular plate during positive displacements of the hair bundle were reversibly abolished in the presence of 100 microM gentamicin and they could not be evoked in 0.1 mM calcium in the external medium. From these experiments, it has been concluded that the [Ca2+]i variations recorded in the cuticular plate were due to a limited entry of calcium ions through transduction channels localized in the hair bundle. The typical kinetics of variations of [Ca2+]i evoked during positive displacements of the hair bundle should account for the presence of strong calcium regulation systems in the hair bundle and cuticular plate.
使用fura - 2快速荧光光度系统，在豚鼠离体前庭感觉细胞的毛束发生机械位移期间，在线记录细胞内游离钙浓度（[Ca2+]i）的变化。毛束反复向动纤毛方向位移（正向刺激7度，300毫秒，2赫兹，持续10秒），结果显示仅在角质板中可检测到[Ca2+]i变化。[Ca2+]i从105 nM增加到145 nM。毛束单次机械位移（7度，200毫秒，0.5赫兹）使[Ca2+]i从50±23 nM增加到139±79 nM（n = 12）。在相反方向，机械刺激（8度，400毫秒，0.5赫兹）使[Ca2+]i从68±17 nM降低到37±12 nM（n = 8）。在毛束正向位移期间在角质板中检测到的[Ca2+]i变化在100 microM庆大霉素存在时可逆性消除，并且在外部培养基中0.1 mM钙的情况下无法诱发。从这些实验得出的结论是，在角质板中记录的[Ca2+]i变化是由于钙离子通过位于毛束中的转导通道有限进入所致。毛束正向位移期间诱发的[Ca2+]i变化的典型动力学应解释毛束和角质板中存在强大的钙调节系统。
