分离的、未固定的小鼠盖膜对等渗溶液的渗透反应：Na⁺、K⁺和Ca²⁺浓度的影响

The osmotic response of the isolated, unfixed mouse tectorial membrane to isosmotic solutions: effect of Na+, K+, and Ca2+ concentration.

作者信息

Shah D M, Freeman D M, Weiss T F

机构信息

Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge 02139, USA.

出版信息

Hear Res. 1995 Jul;87(1-2):187-207. doi: 10.1016/0378-5955(95)00089-m.

DOI:10.1016/0378-5955(95)00089-m

PMID:8567436

Abstract

Changes in the size, shape, and structure of the isolated tectorial membrane (TM) of the mouse were measured in response to isosmotic changes in the ionic composition of the bathing solution. Substitution of artificial perilymph (AP) for artificial endolymph (AE) caused a small (approximately 1%) shrinkage of the TM's thickness. This substitution alters not only the predominate cation (from K+ to Na+) but also the Ca2+ concentration (from 20 mumol/l to 2 mmol/l). When the predominate cation was changed from K+ to Na+, while holding Ca2+ concentration constant, results depended on Ca2+ concentration: there was a small (approximately 1%) swelling for 20 mumol/l Ca2+, larger (approximately 14%) swelling for lower (< 7 mumol/l) concentrations of Ca2+, and little response for 2 mmol/l Ca2+ or for solutions containing the Ca2+ chelator EGTA. Addition of Ca2+ while holding the predominate cation constant caused shrinkage of the TM; both removal of Ca2+ and addition of the Ca2+ chelator EGTA caused swelling. Swelling responses were largely reversible if the magnitude of the swelling was small. Responses greater than a few percent were only partially reversible and caused long-lasting changes. Changes in ionic composition of the bath affected not only the thickness of the TM but also its other dimensions. Solution changes that increase TM thickness tend to cause radial shearing motions of the surfaces of the TM, which are accompanied by small decreases in width. Little change in length was observed. Although the responses were non-isotropic, increases in thickness were highly correlated with increases in volume. Swelling of the TM was also accompanied by a reduction in prominence of its radially oriented fibrillar structure. These results for the isolated TM of the mouse are qualitatively similar to those obtained previously for the isolated chick TM (Freeman et al., 1994) but different from those obtained for the in vitro mouse TM (Kronester-Frei, 1979a).

摘要

在响应浸泡溶液离子组成的等渗变化时，对分离出的小鼠盖膜（TM）的大小、形状和结构变化进行了测量。用人造外淋巴（AP）替代人造内淋巴（AE）会导致TM厚度出现小幅（约1%）收缩。这种替代不仅改变了主要阳离子（从K⁺变为Na⁺），还改变了Ca²⁺浓度（从20 μmol/L变为2 mmol/L）。当主要阳离子从K⁺变为Na⁺，同时保持Ca²⁺浓度恒定时，结果取决于Ca²⁺浓度：对于20 μmol/L的Ca²⁺，会有小幅（约1%）肿胀；对于较低（<7 μmol/L）浓度的Ca²⁺，肿胀幅度更大（约14%）；而对于2 mmol/L的Ca²⁺或含有Ca²⁺螯合剂乙二醇双四乙酸（EGTA）的溶液，几乎没有反应。在保持主要阳离子恒定的情况下添加Ca²⁺会导致TM收缩；去除Ca²⁺以及添加Ca²⁺螯合剂EGTA都会导致肿胀。如果肿胀幅度较小，肿胀反应在很大程度上是可逆的。大于百分之几的反应只是部分可逆，并会导致长期变化。浴液离子组成的变化不仅影响TM的厚度，还影响其其他尺寸。增加TM厚度的溶液变化往往会导致TM表面的径向剪切运动，同时宽度会有小幅减小。未观察到长度有明显变化。尽管这些反应是非各向同性的，但厚度增加与体积增加高度相关。TM肿胀还伴随着其径向排列的纤维状结构的突出程度降低。小鼠分离出的TM的这些结果在定性上与先前从分离出的鸡TM获得的结果相似（弗里曼等人，1994年），但与体外小鼠TM获得的结果不同（克龙斯特 - 弗赖，1979a）。