Blumenthal S S, Ware R A, Kleinman J G
Am J Physiol. 1983 May;244(5):C331-5. doi: 10.1152/ajpcell.1983.244.5.C331.
The effects of directed Na+ gradients on proximal tubule cell transport processes were examined in suspensions of rabbit renal tubules depleted of ATP. Cells of high-Na+ content were generated by suspending the tubules in high-Na+ media, whereas low-Na+ cells were produced by incubating tubules in Na+-free media. Resuspension of the high-Na+ tubules in Na+-free media caused a fall in cell pH simultaneous with a fall in cell Na+. Resuspending the low-Na+ cells in Na+-replete media led to a rise in cell pH, in parallel with the rise in cell Na+. Removing HCO-3 and CO2 augmented and amiloride inhibited the increase in cell pH generated by the inward Na+ gradient. Low-Na+ tubules exposed to an inwardly directed Na+ gradient also concentrated the sugar analogue alpha-methylglucoside, and this uptake was blocked by phlorizin. These findings demonstrate the suitability of ATP-depleted renal tubules for the study of linked transport processes by providing evidence for the existence of the proximal luminal transport processes, Na+-H+ exchange, and Na+-sugar cotransport in this preparation.
在消耗ATP的兔肾小管悬浮液中，研究了定向Na⁺梯度对近端小管细胞转运过程的影响。通过将肾小管悬浮在高Na⁺培养基中来产生高Na⁺含量的细胞，而通过在无Na⁺培养基中孵育肾小管来产生低Na⁺细胞。将高Na⁺肾小管重悬于无Na⁺培养基中会导致细胞pH值下降，同时细胞Na⁺含量也下降。将低Na⁺细胞重悬于富含Na⁺的培养基中会导致细胞pH值升高，与细胞Na⁺含量的升高同时出现。去除HCO₃⁻和CO₂会增强，而氨氯吡咪会抑制由内向Na⁺梯度产生的细胞pH值升高。暴露于内向Na⁺梯度的低Na⁺肾小管也会浓缩糖类似物α-甲基葡萄糖苷，并且这种摄取被根皮苷阻断。这些发现通过为该制剂中近端管腔转运过程、Na⁺-H⁺交换和Na⁺-糖共转运的存在提供证据，证明了消耗ATP的肾小管适用于研究相关的转运过程。
