EXPERIMENTAL DEPRESSION OF JUNCTIONAL MEMBRANE-PERMEABILITY IN MAMMALIAN-CELL CULTURE - STUDY WITH TRACER MOLECULES IN THE 300 TO 800 DALTON RANGE
EXPERIMENTAL DEPRESSION OF JUNCTIONAL MEMBRANE-PERMEABILITY IN MAMMALIAN-CELL CULTURE - STUDY WITH TRACER MOLECULES IN THE 300 TO 800 DALTON RANGE
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DOI：
10.1007/bf01868788
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发表时间：
1979-01-01
影响因子：
2.4
通讯作者：
LOEWENSTEIN, WR
中科院分区：
文献类型：
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作者：
FLAGGNEWTON, J;LOEWENSTEIN, WR
在代谢抑制剂、钙转运离子载体和二氧化碳处理过程中，用300到800 mW的荧光示踪剂探测了哺乳动物[大鼠上皮样RL细胞和成纤维细胞B细胞]细胞对细胞连接的通透性。用氰化物和碘乙酸(各1-2 mM)联合处理，而不是单独用其中任何一种处理，对所有示踪分子物种，无论大小，都造成可逆的连接阻塞。(在测试的结点中有一部分持续存在电耦合)。用电离团A23187(2-10 mm)或用二氧化碳(与介质平衡的100%二氧化碳气氛)处理产生选择性交界性阻塞：688和817-道尔顿示踪剂的传输一般被阻断，而376-道尔顿示踪剂和在某些条件下，559-道尔顿示踪剂的传输持续。离子载体的连接效应需要在外部介质中存在钙，而有效的连接阻断需要在高钙浓度的介质中进行预处理，或者交替地在高CO2浓度的介质中进行预处理。在1种细胞类型中，仅长时间暴露在高钙浓度的介质中就足以阻断688-道尔顿示踪剂的传递。根据结合通透性调节的钙假说，讨论了这些效应。与哺乳动物(或其他脊椎动物和无脊椎动物)有组织的组织培养或昆虫[同翅目叶蝉成纤维细胞AC-20细胞]培养相比，哺乳动物细胞培养更能抵抗连接阻断。这种传递稳定性的差异是根据连接部位的细胞内钙缓冲能力来讨论的；特别是在哺乳动物培养中通过缝隙连接连接的细小的双侧细胞突起的EM发现方面。
Cell-to-cell junctional permeability in mammalian [rat epithelioid liver RL cells, and fibroblast B cells] cell cultures was probed with fluorescent tracers ranging 300 to 800 in MW, during treatment with metabolic inhibitors, Ca-transporting ionophore, and CO2. Treatment with the combination of cyanide and iodoacetic acid (1-2 mM each), but not with either one alone, caused reversible junctional blockade to all tracer molecular species, large and small. (Electrical coupling persisted in a proportion of the junctions tested). Treatment with the ionophore A23187 (2-10 mM) or with CO2 (an atmosphere of 100% CO2 equilibrated with the medium) produced selective junctional blockade: transmission of a 688 and an 817-dalton tracer was generally blocked, while that of a 376-dalton tracer and, in certain conditions, that of a 559-dalton one, persisted. The junctional effect of the ionophore required the presence of Ca in the external medium; and effective junctional blockade by CO2 required pretreatment in medium with high Ca concentration or, interchangeably, pretreatment in medium with high CO2 concentration. In 1 cell type, prolonged exposure to medium with high Ca concentration alone sufficed to block transmission of the 688-dalton tracer. These effects are discussed in terms of the Ca hypothesis of junctional permeability regulation. Compared to mammalian (or other vertebrate and invertebrate) organized tissues or with insect [homoptera leafhopper (Agallia constricta) fibroblast AC-20 cells] cell cultures, the mammalian cell cultures are more resistant to junctional blockade. This difference in transmission stability is discussed in terms of intracellular Ca-buffering capacities of the junctional locales; in particular, in terms of the EM finding in the mammalian cultures of fine, bilateral cell processes connected by gap junctions.