来自紫贻贝（达尔文）肌肉纤维中的细胞外空间和扩散屏障。

Muscle fibres from Megabalanus psittacus (Darwin) were used to measure the exchange of Na+ and Ca2+ between intracellular and extracellular compartments. 2. The size of the extracellular space was evaluated directly from electron micrographs at 6.1 +/- 0.5% (percentage of the fibre volume). The more conventional estimates using Na+ and 134Cs+ as space markers gave higher values, namely, 8.9 +/- 0.7 and 9.5 +/- 1.5%. 3. An average value of 9.2% was used to correct the total Na+ and K+ in the muscle fibres and to estimate the intracellular concentrations of Na+ and K+ as 39 +/- 4 and 202 +/- 11 mM respectively. 4. Na+ (and similar Ca2+) washout curves could be described using a three compartments diffusion model. The data analysed in terms of this model enabled us to estimate membrane permeabilities as PNa+ = 2.7 x 10(-7) and PCa2+ = 2.7 x 10(-7) cm/sec.

利用来自紫斑巨藤壶（达尔文）的肌纤维来测量细胞内和细胞外区室之间Na⁺和Ca²⁺的交换。2. 细胞外空间的大小直接从电子显微镜照片评估为6.1±0.5%（纤维体积的百分比）。使用Na⁺和¹³⁴Cs⁺作为空间标记的更传统估计给出了更高的值，即8.9±0.7%和9.5±1.5%。3. 采用9.2%的平均值来校正肌纤维中的总Na⁺和K⁺，并将细胞内Na⁺和K⁺的浓度分别估计为39±4 mM和202±11 mM。4. Na⁺（以及类似的Ca²⁺）洗脱曲线可以用三室扩散模型来描述。根据该模型对数据进行分析使我们能够估计膜渗透率，PNa⁺ = 2.7×10⁻⁷，PCa²⁺ = 2.7×10⁻⁷ cm/秒。

Extracellular space and diffusion barriers in muscle fibres from Megabalanus psittacus (Darwin).