Yang J, Wang J, Wei S
Union Hospital, Tongji Medical University, Wuhan 430022.
Zhonghua Er Bi Yan Hou Ke Za Zhi. 1998 Oct;33(5):279-81.
To measure the effects of neuro-active substances on intracellular free Ca2+ concentration ([Ca2+]i) in isolated outer hair cells(OHCs) of the guinea pig cochlea.
The fura-2 microfluorimetry was used to measure changes of [Ca2+]i in OHCs of the guinea pig cochlea after application of acetylcholine, ATP and carbacholine.
Acetylcholine, ATP and carbacholine increased [Ca2+]i (acetylcholine: 0.74 +/- 0.12 mumol/L, ATP: 0.65 +/- 0.11 mumol/L, carbacholine: 1.16 +/- 0.27 mumol/L) in OHCs in the presence of extracellular Ca2+. In the absence of extracellular Ca2+, however, only ATP induced a gradual and small [Ca2+]i elevation, whereas other substances did not.
Acetylcholine and carbacholine, the cholinergic mascarinic agonists, increased [Ca2+]i in OHCs by acting at receptor-induced ion channel resulting in Ca2+ efflux. ATP-induced elevation of [Ca2+]i without Ca2+ in extracellular medium is due to a release of Ca2+ from an intracellular reservoir.
测量神经活性物质对豚鼠耳蜗孤立外毛细胞（OHC）内游离钙离子浓度（[Ca2+]i）的影响。
采用fura-2显微荧光测定法，测量应用乙酰胆碱、ATP和卡巴胆碱后豚鼠耳蜗OHC中[Ca2+]i的变化。
在细胞外存在Ca2+的情况下，乙酰胆碱、ATP和卡巴胆碱可使OHC中的[Ca2+]i升高（乙酰胆碱：0.74±0.12μmol/L，ATP：0.65±0.11μmol/L，卡巴胆碱：1.16±0.27μmol/L）。然而，在细胞外不存在Ca2+的情况下，只有ATP可诱导[Ca2+]i逐渐小幅升高，而其他物质则无此作用。
胆碱能毒蕈碱激动剂乙酰胆碱和卡巴胆碱通过作用于受体诱导的离子通道导致Ca2+外流，从而使OHC中的[Ca2+]i升高。细胞外培养基中无Ca2+时，ATP诱导的[Ca2+]i升高是由于细胞内储存库释放Ca2+所致。
