SATURATION KINETICS OF SODIUM EFFLUX ACROSS ISOLATED FROG SKIN
SATURATION KINETICS OF SODIUM EFFLUX ACROSS ISOLATED FROG SKIN
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DOI：
10.1152/ajplegacy.1976.231.4.995
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发表时间：
1976-01-01
影响因子：
--
通讯作者：
MULLEN, TL
中科院分区：
文献类型：
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作者：
BIBER, TUL;MULLEN, TL
测量从皮肤侧到外部穿过青蛙皮肤上皮的Na流出。**图形 **。在一个专门设计的避免边缘损坏的新腔室中，图形 **。表现出饱和动力学，最大外排（Jmax）为31.8 nmol/cm 2/h，表观KNa为4.0 mM。图形 **。在常规腔室中测量和在新腔室中测定通过细胞外途径通过上皮的物质（聚乙二醇900、蔗糖、甘露醇）的流出量显示出所讨论的物质的流出量与其在浴中的浓度之间的线性关系。此外，外部钠浓度的变化不会引起显著变化。**图形 **。应用哇巴因后，饱和度保持不变，但Jmax和KNa均增加。阿米洛利以及二硝基苯酚消除了饱和度，图形 **。成了Na浓度的线性函数。哇巴因和阿米洛利的单独作用表明，已知影响主动转运途径中2个明显不同步骤的这2种抑制剂也作用于2个单独的步骤。图形 **。分别穿过上皮细胞的向内的（serum）和向外的（apical）细胞膜。二硝基酚的作用表明代谢参与了。**图形 **。可能是两个步骤中的最后一个。.**图形 **。显然不是通过细胞旁途径而是通过与主动转运途径相互作用的跨细胞途径进行。
Measurement of Na efflux across the frog skin epithelium from the serosal side to the outside .**GRAPHIC**. in a new chamber specifically designed to avoid edge damage showed that .**GRAPHIC**. exhibited saturation kinetics with a maximal efflux (Jmax) of 31.8 nmol/cm2 per h and an apparent KNa of 4.0 mM. In contrast, .**GRAPHIC**. measured in conventional chambers and efflux determinations in the new chamber of substances that pass the epithelium via extracellular pathways (polyethylene glycol 900, sucrose, mannitol) exhibited a linear relationship between the efflux of the substance in question and its concentration in the bath. In addition, changes in external Na concentration did not cause substantial changes in .**GRAPHIC**. The saturation remained but both Jmax and KNa increased after application of ouabain. Amiloride, as well as dinitrophenol, eliminated the saturation and .**GRAPHIC**. became a linear function of Na concentration. The separate effects of ouabain and amiloride suggest that these 2 inhibitors which were known to affect 2 distinctly different steps in the active transport pathway act also on 2 separate steps of .**GRAPHIC**. the passage across the inward- (serosal) and outward-facing (apical) cell membranes of the epithelial cells, respectively. The action of dinitrophenol indicated the involvement of metabolism in .**GRAPHIC**. probably at the latter of the 2 steps. .**GRAPHIC**. apparently proceeds not via a paracellular but via a transcellular pathway that interacts with the active transport pathway.