Birks R I, Davey D F
J Physiol. 1972 Apr;222(1):95-111. doi: 10.1113/jphysiol.1972.sp009789.
The volume responses of the T-system of frog skeletal muscle to isotonic solutions of altered ionic composition, as studied by electron microscopic examination of osmium-fixed tissue, have been re-investigated using aldehyde fixatives.1. In confirmation of the earlier work we find that the T-tubes swell in frog sartorius muscles which have been soaked in Ringer solution in which the sodium chloride concentration has been reduced to 40 mM and tonicity maintained with sucrose before fixation in osmium.2. The swelling does not occur in muscles similarly treated, but fixed with acrolein or glutaraldehyde.3. Swelling of the T-tubes, which has been reported for osmium-fixed muscle following exposure to Ringer in which chloride is replaced by acetate, or reduced and sulphate substituted, does not occur when fixation is by acrolein.4. Analysis of the data from the earlier work with sucrose substitution shows that the degree of T-tube swelling is proportional to the sucrose concentration of the soaking medium, whether the solution be isotonic or anisotonic.5. It is concluded that the increase in T-tube volume arises in muscles which have been exposed to certain impermeant solutes during fixation by osmium, and a possible mechanism to account for the effect is described.6. The relevance of these observations to the hypothesis that the sarcoplasmic reticulum is an extracellular compartment in muscle and to the proposal that the T-tubes may represent an intermediate compartment for potassium fluxes is discussed.
利用醛类固定剂，对蛙骨骼肌T系统对离子成分改变的等渗溶液的容积反应进行了重新研究，该反应最初是通过对锇固定组织的电子显微镜检查来研究的。1. 正如早期研究结果所证实的那样，我们发现，在蛙缝匠肌中，T管会出现肿胀。这些肌肉浸泡在氯化钠浓度降至40 mM的林格氏溶液中，并在锇固定前用蔗糖维持张力。2. 用丙烯醛或戊二醛固定的、经过类似处理的肌肉中不会出现肿胀。3. 据报道，用锇固定的肌肉在暴露于用醋酸盐替代氯离子、或降低氯离子浓度并用硫酸盐替代的林格氏溶液后，T管会肿胀，但用丙烯醛固定时不会出现这种情况。4. 对早期蔗糖替代研究数据的分析表明，T管肿胀程度与浸泡介质中的蔗糖浓度成正比，无论溶液是等渗还是非等渗。5. 由此得出结论，T管容积的增加出现在用锇固定期间暴露于某些非渗透性溶质的肌肉中，并描述了一种可能解释这种效应的机制。6. 讨论了这些观察结果与肌浆网是肌肉细胞外区室这一假说的相关性，以及T管可能代表钾离子通量中间区室这一观点的相关性。
