Stirling C E
J Cell Biol. 1972 Jun;53(3):704-14. doi: 10.1083/jcb.53.3.704.
Direct demonstration of the cellular location of sodium pumping constitutes a key problem in the solution of intestinal sodium absorption. Utilizing silicone-impregnated epoxy sections of freeze-dried, osmium-fixed tissue, ouabain-(3)H and inulin-(3)H light microscope radioautographs have been produced which show that: lateral but not brush border membranes of rabbit small intestine bind ouabain-(3)H (high specific activity) with an affinity so great that a subsequent washing in ouabain-free medium has little effect on binding; lateral membrane binding is not apparent with low specific activity ouabain-(3)H, and inulin-(3)H and ouabain-(3)H (low specific activity) in the cores of the villi do not equilibrate with the intercellular spaces. Preliminary tracer measurements of ouabain-(3)H and inulin-(14)C spaces also agree with these findings As ouabain is a specific inhibitor of active sodium transport, these observations provide direct support for the view that lateral membrane pumping of sodium into the intercellular spaces causes, through osmotic forces on water, a flow of fluid out of these spaces into the interstitium.
直接证明钠泵的细胞定位是解决肠道钠吸收问题的关键所在。利用冻干、锇固定组织的硅浸渍环氧树脂切片，制作了哇巴因 -（³H）和菊粉 -（³H）光学显微镜放射自显影片，结果显示：兔小肠的侧膜而非刷状缘膜能以极高的亲和力结合高比活度的哇巴因 -（³H），以至于随后在无哇巴因培养基中洗涤对结合影响很小；低比活度的哇巴因 -（³H）未显示侧膜结合，且绒毛核心中的菊粉 -（³H）和低比活度的哇巴因 -（³H）不会与细胞间隙达到平衡。对哇巴因 -（³H）和菊粉 -（¹⁴C）空间的初步示踪测量结果也与这些发现相符。由于哇巴因是主动钠转运的特异性抑制剂，这些观察结果直接支持了以下观点：钠向细胞间隙的侧膜泵入通过对水的渗透力，导致液体从这些间隙流向间质。
