Chen C, LeBlanc C, Bobbin R P
Kresge Hearing Research Laboratory of the South, Department of Otorhinolaryngology and Biocommunication, Louisiana State University Medical Center, New Orleans 70112-2234, USA.
Hear Res. 1997 Aug;110(1-2):87-94. doi: 10.1016/s0378-5955(97)00069-5.
Adenosine 5' triphosphate (ATP) and acetylcholine (ACh) are neurotransmitters (ACh) and/or modulators (ATP) in the mammalian cochlea. In guinea pig, it appears that both neurotransmitters have a similar response distribution, with larger responses being evoked by the ligands in short hair cells compared to long hair cells (e.g., Chen et al., 1995b. Noise exposure alters the response of outer hair cells to ATP. Hear. Res. 88, 215-221.; Erostegui et al., 1994. In vitro pharmacologic characterization of a cholinergic receptor on outer hair cells. Hear. Res. 74, 135 147). The purpose of the present study was to test whether the distribution of responses to ACh and ATP in the OHCs of rat is the same as guinea pig. The ligand-induced current was monitored using the whole-cell configuration of the patch-clamp technique. Results show that in guinea pig OHCs, extracellular application of 100 microM ATP induced a current response in a majority of the same cells that responded to the application of 100 microM ACh. In contrast in rat OHCs, 100 microM ATP did not induce a current in the majority of cells that responded to the application of 100 microM ACh. N-methyl-glucamine (NMG+) substituted for K+ in the pipette solution failed to unmask an ATP-evoked inward current in rat OHCs. In addition, no response was produced in rat or guinea pig OHCs by adenosine, adenosine 5'-monophosphate (AMP) or adenosine 5'-diphosphate (ADP) at 100 microM. Results suggest that in guinea pig ACh-gated channels are present on most of the same OHCs that have ATP-gated ion channels, whereas in rat ACh-gated ion channels are present without ATP-gated channels on some OHCs.
三磷酸腺苷（ATP）和乙酰胆碱（ACh）是哺乳动物耳蜗中的神经递质（ACh）和/或调质（ATP）。在豚鼠中，这两种神经递质似乎具有相似的反应分布，与长纤毛细胞相比，短纤毛细胞对配体的反应更大（例如，Chen等人，1995b。噪声暴露改变外毛细胞对ATP的反应。听觉研究。88，215 - 221；Erostegui等人，1994。外毛细胞上胆碱能受体的体外药理学特征。听觉研究。74，135 - 147）。本研究的目的是测试大鼠外毛细胞中对ACh和ATP的反应分布是否与豚鼠相同。使用膜片钳技术的全细胞配置监测配体诱导的电流。结果表明，在豚鼠外毛细胞中，细胞外施加100微摩尔ATP在大多数对施加100微摩尔ACh有反应的相同细胞中诱导了电流反应。相比之下，在大鼠外毛细胞中，100微摩尔ATP在大多数对施加100微摩尔ACh有反应的细胞中未诱导电流。移液管溶液中用N - 甲基葡糖胺（NMG +）替代K +未能揭示大鼠外毛细胞中ATP诱发的内向电流。此外，100微摩尔的腺苷、5'-单磷酸腺苷（AMP）或5'-二磷酸腺苷（ADP）在大鼠或豚鼠外毛细胞中均未产生反应。结果表明，在豚鼠中，大多数具有ATP门控离子通道的相同外毛细胞上存在ACh门控通道，而在大鼠中，一些外毛细胞上存在ACh门控离子通道但没有ATP门控通道。
