Kahn A M, Weinman E J
Am J Physiol. 1985 Dec;249(6 Pt 2):F789-98. doi: 10.1152/ajprenal.1985.249.6.F789.
The transport of urate in the mammalian nephron is largely confined to the proximal tubule. Depending on the species, net reabsorption or net secretion is observed. The rat, like the human and the mongrel dog, demonstrates net reabsorption of urate and has been the most extensively studied species. The unidirectional reabsorption and secretion of urate in the rat proximal tubule occur via a passive and presumably paracellular route and by a mediated transcellular route. The reabsorption of urate, and possibly its secretion, can occur against an electrochemical gradient. A variety of drugs and other compounds affect the reabsorption and secretion of urate. The effects of these agents depend on their site of application (luminal or blood), concentration, and occasionally their participation in transport processes that do not have affinity for urate. Recent studies with renal brush border and basolateral membrane vesicles from the rat and brush border vesicles from the dog have determined the mechanisms for urate transport across the luminal and antiluminal membranes of the proximal tubule cell. Brush border membrane vesicles contain an anion exchanger with affinity for urate, hydroxyl ion, bicarbonate, chloride, lactate, p-aminohippurate (PAH), and a variety of other organic anions. Basolateral membrane vesicles contain an anion exchanger with affinity for urate and chloride but not for PAH. Both membrane vesicle preparations also permit urate translocation by simple diffusion. A model for the transcellular reabsorption and secretion of urate in the rat proximal tubule is proposed. This model is based on the vesicle studies, and it can potentially explain the majority of urate transport data obtained with in vivo techniques.
哺乳动物肾单位中尿酸盐的转运主要局限于近端小管。根据物种不同，可观察到尿酸盐的净重吸收或净分泌。大鼠与人类和杂种狗一样，表现出尿酸盐的净重吸收，并且是研究最为广泛的物种。大鼠近端小管中尿酸盐的单向重吸收和分泌通过被动且可能是细胞旁途径以及介导的跨细胞途径进行。尿酸盐的重吸收以及可能的分泌能够逆电化学梯度发生。多种药物和其他化合物会影响尿酸盐的重吸收和分泌。这些药剂的作用取决于它们的应用部位（管腔或血液）、浓度，偶尔还取决于它们参与对尿酸盐无亲和力的转运过程。最近对大鼠肾刷状缘和基底外侧膜囊泡以及狗的刷状缘囊泡的研究确定了尿酸盐跨近端小管细胞管腔和反管腔膜转运的机制。刷状缘膜囊泡含有一种对尿酸盐、氢氧根离子、碳酸氢根、氯离子、乳酸、对氨基马尿酸（PAH）以及多种其他有机阴离子具有亲和力的阴离子交换器。基底外侧膜囊泡含有一种对尿酸盐和氯离子具有亲和力但对PAH无亲和力的阴离子交换器。两种膜囊泡制剂也都允许尿酸盐通过简单扩散进行转运。本文提出了大鼠近端小管中尿酸盐跨细胞重吸收和分泌的模型。该模型基于囊泡研究，并且有可能解释通过体内技术获得的大多数尿酸盐转运数据。
