White P N, Thorne P R, Housley G D, Mockett B, Billett T E, Burnstock G
Department of Physiology, University of Auckland, New Zealand.
Hear Res. 1995 Oct;90(1-2):97-105. doi: 10.1016/0378-5955(95)00151-1.
There is accumulating evidence for a purinergic humoral system involved in the control of cochlear function. Evidence of specific P2 purinoceptors on cochlear tissues implies a role for extracellular adenosine triphosphate (ATP) in the cochlea. To further this hypothesis a study was undertaken to determine if there was any specific source of purine compounds in cochlear tissues. Cochlear tissues (the sensory epithelium and lateral wall) from the guinea pig were incubated with the acridine derivative quinacrine dihydrochloride (5 x 10(-6) M in phosphate-buffered saline for 30 min at room temperature) which fluoresces on binding to high concentrations of ATP. Most cochlear tissues showed a diffuse green fluorescence slightly above the background level. However, a region of the marginal cells of the stria vascularis showed a specific punctate fluorescence. Optical sectioning of these cells by confocal microscopy revealed that the fluorescent structures in these marginal cells was confined to a region up to 10 microns from their endolymphatic surface. Similar cells studied by transmission electron microscopy showed membrane-bound vesicles located in the same region of the cell. These data imply that purine compounds are localized in discrete structures, perhaps vesicles, within the marginal cells which could serve as a source of extracellular ATP in the cochlea.
越来越多的证据表明，存在一个参与耳蜗功能控制的嘌呤能体液系统。耳蜗组织上特定P2嘌呤受体的证据表明细胞外三磷酸腺苷（ATP）在耳蜗中发挥作用。为了进一步验证这一假设，开展了一项研究，以确定耳蜗组织中是否存在嘌呤化合物的特定来源。将豚鼠的耳蜗组织（感觉上皮和侧壁）与吖啶衍生物盐酸喹吖因（在磷酸盐缓冲盐水中浓度为5×10⁻⁶ M，室温下孵育30分钟）一起孵育，该衍生物在与高浓度ATP结合时会发出荧光。大多数耳蜗组织显示出略高于背景水平的弥漫性绿色荧光。然而，血管纹边缘细胞的一个区域显示出特定的点状荧光。通过共聚焦显微镜对这些细胞进行光学切片显示，这些边缘细胞中的荧光结构局限于距其内淋巴表面10微米以内的区域。通过透射电子显微镜研究的类似细胞显示，膜结合囊泡位于细胞的同一区域。这些数据表明，嘌呤化合物定位于边缘细胞内离散的结构中，可能是囊泡，这可能是耳蜗中细胞外ATP的来源。
