Wedeen R P, Vyas B T
Kidney Int. 1978 Aug;14(2):158-68. doi: 10.1038/ki.1978.103.
Phlorizin, 0.5 mM, increases the uptake of tritiated p-aminohippuric acid (PAH) in rat kidney cortex slices in vitro. Phlorizin also diminishes the rate of 3H-PAH washout from preloaded slices into PAH-free medium. At higher concentrations, phlorizin (5.0 mM) reduces slice uptake of 3H-PAH following short incubations but increases 3H-PAH accumulation after more prolonged incubations. Section freeze-dry autoradiography demonstrates that phlorizin inhibits secretion of 3H-PAH from cell to lumen in proximal tubules. Consequently, the increased 3H-PAH uptake and delayed washout induced by phlorizin may be attributed to effects at the antiluminal cell membrane. Phlorizin stimulation of PAH uptake occurs despite inhibition of secretion across the luminal membrane. Intracellular accumulation of 3H-phlorizin, demonstrable by autoradiography, provides direct evidence that cellular accumulation affords the glycoside access to both the luminal and antiluminal membrane in proximal tubules. These interactions between phlorizin and PAH suggest shared features of the membrane transport systems for secretion and reabsorption of sugars and organic acids in kidney.
0.5毫摩尔的根皮苷可增加体外培养的大鼠肾皮质切片对氚标记对氨基马尿酸（PAH）的摄取。根皮苷还可降低预先加载的切片中3H-PAH洗脱至不含PAH的培养基中的速率。在较高浓度下，根皮苷（5.0毫摩尔）在短期孵育后会降低切片对3H-PAH的摄取，但在更长时间孵育后会增加3H-PAH的积累。切片冷冻干燥放射自显影显示，根皮苷抑制近端小管中3H-PAH从细胞向管腔的分泌。因此，根皮苷诱导的3H-PAH摄取增加和洗脱延迟可能归因于其对细胞抗腔面膜的作用。尽管根皮苷抑制了跨腔面膜的分泌，但它仍能刺激PAH的摄取。放射自显影显示可检测到细胞内3H-根皮苷的积累，这直接证明了细胞积累使糖苷能够进入近端小管的腔膜和抗腔膜。根皮苷与PAH之间的这些相互作用表明，肾脏中糖和有机酸分泌与重吸收的膜转运系统具有共同特征。
