Muffly K E, Hall P F
Worcester Foundation for Experimental Biology, Shrewsbury, Massachusetts 01545.
Endocrinology. 1988 Oct;123(4):2083-8. doi: 10.1210/endo-123-4-2083.
Sertoli cells from rats aged 25 days were grown on Millipore filters (pore diameter 0.5 micron) for 7 days and were then used for determination of transport of 86Rb+ through the cells (base to apex); this procedure is referred to as measuring transcellular or vectorial transport. Sertoli cells were also used to measure apical efflux of 86Rb+ by loading the cells with the isotope to steady state and then incubating cells so that the apical surfaces were in contact with medium not containing 86Rb+, from which samples were taken. Basal efflux was measured in the same way except that the opposite surface of the cells was in contact with the medium. Cells grown on filters treated with collagen IV plus fibronectin showed transcellular transport of 86Rb+; t1/2 for equilibration across the cells was 9-12 min. The rate of transport was accelerated by addition of (Bu)2cAMP, forskolin, or FSH to the incubation medium. Half-maximal responses were seen with (Bu)2cAMP at 0.2 mM and with forskolin at 20 microM. Apical efflux (t1/2 9.8 +/- 2.1 min) was not influenced by the presence or absence of K+ in the medium nor by azide or (Bu)2cAMP. Basal efflux showed similar values for t1/2 in the presence of K+ (9.7 +/- 1.9 min) and values of 21.4 +/- 4.2 min in the absence of K+. Vectorial transport of 86Rb+ by these cells may account for the K+ gradient seen in the seminiferous tubule and appears to result from a basolateral potassium pump together with an apical membrane that is permeable to K+.
将25日龄大鼠的支持细胞接种在孔径为0.5微米的密理博滤膜上培养7天，然后用于测定⁸⁶Rb⁺通过细胞（从基底侧到顶端）的转运；此过程称为测量跨细胞或向量转运。支持细胞还用于通过将细胞用该同位素加载至稳态，然后孵育细胞以使顶端表面与不含⁸⁶Rb⁺的培养基接触，并从中取样来测量⁸⁶Rb⁺的顶端流出。基底侧流出的测量方式相同，只是细胞的相对表面与培养基接触。在经IV型胶原蛋白加纤连蛋白处理的滤膜上生长的细胞表现出⁸⁶Rb⁺的跨细胞转运；跨细胞平衡的半衰期为9 - 12分钟。向孵育培养基中添加（Bu）₂cAMP、福斯可林或促卵泡激素可加速转运速率。（Bu）₂cAMP在0.2 mM时和福斯可林在20 μM时出现半数最大反应。顶端流出（半衰期9.8 ± 2.1分钟）不受培养基中K⁺的存在与否、叠氮化物或（Bu）₂cAMP的影响。在有K⁺存在时基底侧流出的半衰期显示出相似的值（9.7 ± 1.9分钟），而在无K⁺时为21.4 ± 4.2分钟。这些细胞对⁸⁶Rb⁺的向量转运可能解释了在生精小管中看到的K⁺梯度，并且似乎是由基底外侧钾泵以及对K⁺通透的顶端膜共同导致的。
