外部钙离子对藤壶肌肉细胞水通透性、调节性容积减小和细胞外空间的影响。
External Ca effect on water permeability, regulatory volume decrease, and extracellular space in barnacle muscle cells.
作者信息
Berman D M, Peña-Rasgado C, Holmgren M, Hawkins P, Rasgado-Flores H
机构信息
Department of Physiology and Biophysics, University of Health Sciences Chicago Medical School, Illinois 60064.
出版信息
Am J Physiol. 1993 Oct;265(4 Pt 1):C1128-37. doi: 10.1152/ajpcell.1993.265.4.C1128.
The effect of extracellular Ca2+ (Cao) on sarcolemmal hydraulic water permeability (L'p), regulatory volume decrease (RVD), and extracellular space (ECS) was studied in barnacle muscle cells. Absence or presence of Cao had no effect on L'p [0 Cao = 2.762 +/- 0.098 x 10(-5), and 11 mM Cao = 2.720 +/- 0.222 x 10(-5) cm.kg.s-1 x osmol x 1-kgH2O-1]. Likewise, cells exposed to anisosmotic media (for < 30 min) behaved as osmometers in 0 and 11 mM Cao, showing similar slopes and intercepts in van't Hoff plots. At longer incubation times, however, hyposmotic conditions promoted a Cao-dependent RVD. The relationship between Cao and the percentage of cells responding with RVD to a hyposmotic challenge was sigmoidal (half-maximal Cao = 4.83 mM). The mean rate of RVD (40 nl/min) was independent of the level of swelling in response to hyposmotic challenges. However, the magnitude of RVD increased with larger hyposmotic challenges. Both the presence of Cao and hypotonicity reduced the "apparent" ECS by 47 +/- 6 and 39 +/- 6%, respectively. Three-dimensional reconstruction of autoradiographs of the cells was made to interpret these results.
在藤壶肌细胞中研究了细胞外钙离子（Ca₂⁺）对肌膜水力水通透性（L'p）、调节性容积减小（RVD）和细胞外间隙（ECS）的影响。有无Ca₂⁺对L'p均无影响[无Ca₂⁺时L'p = 2.762 ± 0.098×10⁻⁵，11 mM Ca₂⁺时L'p = 2.720 ± 0.222×10⁻⁵ cm·kg·s⁻¹×渗透压×1 kgH₂O⁻¹]。同样，暴露于非等渗介质（< 30分钟）的细胞在0和11 mM Ca₂⁺中表现为渗透计，在范特霍夫图中显示出相似的斜率和截距。然而，在较长孵育时间下，低渗条件促进了依赖Ca₂⁺的RVD。Ca₂⁺与对低渗刺激产生RVD反应的细胞百分比之间的关系呈S形（Ca₂⁺半最大值 = 4.83 mM）。RVD的平均速率（40 nl/分钟）与低渗刺激引起的肿胀程度无关。然而，RVD的幅度随更大的低渗刺激而增加。Ca₂⁺的存在和低渗性分别使“表观”ECS降低了47 ± 6%和39 ± 6%。对细胞放射自显影片进行三维重建以解释这些结果。
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