Caillé J P
Can J Physiol Pharmacol. 1984 Mar;62(3):329-33.
The thermodynamically effective charge density (phi X) of myoplasm was measured on barnacle muscle fibers. A small section of a muscle cell formed a liquid junction between two electrolyte solutions and the electrical potential between the solutions permitted to evaluate phi X. If the sarcomere length was kept constant (Ls = 12.5 micron), phi X increased from 0.068 to 0.090 equiv./L when the water content was reduced from 75 to 65 g/100 g wet weight. This increment of X resulted from an increase of X when the concentration of macromolecules is raised in the sample of cytoplasm. But it also indicates that the counterions of the fixed charges concur less to the activity of the counterions when X is increased by lowering the water content. If the water content is maintained constant, phi X increased from 0.068 to 0.084 equiv./L for sarcomere lengths equal to 9.6 and 11.5 micron but phi X remained constant for Ls greater than 12 micron. Thus, when the length of the sarcomere is greater than 12 micron the contribution of the counterions of the fixed charges to the activity of the counterion is larger than for Ls = 9.6 micron.
在藤壶肌纤维上测量了肌质的热力学有效电荷密度（φX）。一小段肌肉细胞在两种电解质溶液之间形成了液体接界，溶液之间的电势可用于评估φX。如果肌节长度保持恒定（Ls = 12.5微米），当含水量从75克/100克湿重降至65克/100克湿重时，φX从0.068增加到0.090当量/升。X的这种增加是由于细胞质样品中大分子浓度升高时X增加所致。但这也表明，当通过降低含水量使X增加时，固定电荷的抗衡离子对抗衡离子活性的贡献减小。如果含水量保持恒定，对于肌节长度分别为9.6和11.5微米，φX从0.068增加到0.084当量/升，但当Ls大于12微米时，φX保持恒定。因此，当肌节长度大于12微米时，固定电荷的抗衡离子对抗衡离子活性的贡献比Ls = 9.6微米时更大。
