Endo M, Yagi S, Iino M
Fed Proc. 1982 May;41(7):2245-50.
Properties of bundles of smooth muscle fibers in which the surface membrane has been rendered highly permeable by chemical treatment (saponin) are described. These preparations are termed chemically skinned smooth muscle fiber bundles. Thin bundles were isolated from guinea pig teniae ceci and skinned in a relaxing solution by treatment with 50 micrograms/ml saponin for 20-30 min. Because Ca2+ sensitivity progressively decreased on repeating contractions or on incubating in a relaxing solution, the tension-pCa (-log10 [free Ca2+]) relationship was determined soon after the skinning by a single contraction in which the [free Ca2+] was increased in a stepwise manner. Unlike skinned skeletal muscle fibers, in skinned smooth muscle fiber bundles the tension-pCa relationship was not affected appreciably by the changes in pH from 6.4 to 7.2, in ionic strength from 0.15 to 0.30 M, or in [MgATP] from 0.4 to 8 mM. The saponin-treated smooth muscle fiber bundles retained a functional sarcoplasmic reticulum (SR). Ca can be loaded in the SR if the [free Ca2+] is in the micromolar range and MgATP is present and can be released by an application of caffeine. Mitochondria also appear to be functional in saponin-treated fibers.
描述了经化学处理（皂角苷）使表面膜具有高渗透性的平滑肌纤维束的特性。这些制剂被称为化学去膜平滑肌纤维束。从豚鼠盲肠带分离出细纤维束，并用50微克/毫升皂角苷在松弛溶液中处理20 - 30分钟使其去膜。由于重复收缩或在松弛溶液中孵育时Ca2 +敏感性逐渐降低，去膜后通过单次收缩以逐步增加[游离Ca2 +]的方式测定张力-pCa（-log10 [游离Ca2 +]）关系。与去膜骨骼肌纤维不同，在去膜平滑肌纤维束中，pH从6.4变为7.2、离子强度从0.15变为0.30 M或[MgATP]从0.4变为8 mM的变化对张力-pCa关系没有明显影响。经皂角苷处理的平滑肌纤维束保留了功能性肌浆网（SR）。如果[游离Ca2 +]处于微摩尔范围内且存在MgATP，Ca可加载到SR中，并可通过施加咖啡因释放。线粒体在经皂角苷处理的纤维中似乎也具有功能。
