Shiga N
Department of Otolaryngology, Fukushima Rosai Hospital, Iwaki.
Nihon Jibiinkoka Gakkai Kaiho. 1996 Jun;99(6):895-909. doi: 10.3950/jibiinkoka.99.895.
The volume response of vestibular dark cells of the gerbil to a hyposmotic challenge was investigated. Tissues including dark cells were perfused in preparations in which the perfusate had access to both sides of the epithelium and the height of the dark cell layer was measured as an indicator of its volume. We found that dark cells showed a fast and strong regulatory volume decrease (RVD) and prevented cell swelling in hypotonic media. This mechanism was dependent upon extracellular [K+] and [Cl-]. Ion selectivity of this mechanism was K+ = Rb+ > Cs+ > Na+ = NMDG+ (N-methyl-D-glucamine) for cations and Cl- = SCN- = NO3- > > gluconate- for anions. RVD of dark cells was inhibited by K(+)- channel blockers barium, quinidine and lidocaine, by Cl(-)-channel blockers 4-acetamido-4'-isothiocyanatostilbene-2,2'-disulfonic acid and 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid, by an Na(+)-K+ ATPase inhibitor ouabain and by low temperature, but was not inhibited by a loop diuretic bumetanide, by carbonic anhydrase inhibitors acetazolamide and ethoxyzolamide, by a K(+)-channel blocker tetraethylammonium, by a Cl(-)-channel blocker 5-nitro-2 (3-phenylpropylamino)-benzoic acid or by an inhibitor of the Na(+)-H+ exchanger amiloride. These data suggest that the RVD of dark cells occurs via separate K+ and Cl- channels which are different from those active under isosmotic condition, and is presumably activated by a hyposmotic stimulus.
研究了沙鼠前庭暗细胞对低渗刺激的容积反应。将包括暗细胞的组织在制备物中进行灌注，在该制备物中灌注液可接触上皮细胞的两侧，并测量暗细胞层的高度作为其容积的指标。我们发现暗细胞表现出快速而强烈的调节性容积减小（RVD），并在低渗介质中防止细胞肿胀。该机制依赖于细胞外的[K⁺]和[Cl⁻]。该机制对阳离子的离子选择性为K⁺ = Rb⁺ > Cs⁺ > Na⁺ = NMDG⁺（N-甲基-D-葡糖胺），对阴离子为Cl⁻ = SCN⁻ = NO₃⁻ >> 葡萄糖酸盐⁻。暗细胞的RVD受到K⁺通道阻滞剂钡、奎尼丁和利多卡因、Cl⁻通道阻滞剂4-乙酰氨基-4'-异硫氰酸根合芪-2,2'-二磺酸和4,4'-二异硫氰酸根合芪-2,2'-二磺酸、Na⁺-K⁺ ATP酶抑制剂哇巴因以及低温的抑制，但不受袢利尿剂布美他尼、碳酸酐酶抑制剂乙酰唑胺和乙氧唑酰胺、K⁺通道阻滞剂四乙铵、Cl⁻通道阻滞剂5-硝基-2（3-苯丙基氨基）-苯甲酸或Na⁺-H⁺交换体抑制剂氨氯吡咪的抑制。这些数据表明，暗细胞的RVD通过与等渗条件下活跃的通道不同的独立K⁺和Cl⁻通道发生，并且可能由低渗刺激激活。
