Urate transport via anion exchange in dog renal microvillus membrane vesicles.
Urate transport via anion exchange in dog renal microvillus membrane vesicles.
复制标题
狗肾微绒毛膜囊泡中通过阴离子交换的尿酸盐转运。
DOI：
10.1152/ajprenal.1983.244.1.f56
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发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Aronson,PS
中科院分区：
文献类型：
--
作者：
Kahn,AM;Aronson,PS
从狗肾皮质分离的刷状缘膜囊泡中评价尿酸盐的转运。以前的研究表明，上坡的尿酸和对氨基马尿酸(PAH)摄取到这些膜小泡是由于施加了向外定向的OH-梯度。在本研究中，外部Cl-抑制了OH-梯度刺激的尿酸盐摄取。在没有OH-梯度的情况下，施加向外的Cl-梯度会导致尿酸盐相对于其浓度梯度(超调)的瞬时积累，而施加向内的Cl-梯度会导致尿酸盐的瞬时上坡外流(超调)。当在K+离子载体呋喃霉素存在的情况下，通过叠加K+梯度来抵消由Cl-梯度引起的扩散势时，Cl-梯度对尿酸盐转运的影响仍然存在。三种不同抑制剂对OH-和Cl-梯度刺激的尿酸盐摄取模式的剂量-反应曲线是相同的。多环芳烃的摄取也通过施加向外定向的氯离子梯度而被刺激。羟基和氯离子梯度刺激的多环芳烃摄取模式下，丙磺舒抑制作用的剂量-反应曲线相同。最后，不能证明尿酸盐或多环芳烃存在Na+共转运途径。我们认为狗肾微绒毛膜囊中尿酸盐转运的主要机制是通过与尿酸盐、多环芳烃、OH-和Cl-有亲和力的阴离子交换剂。这种阴离子交换器可能在介导近端小管有机阴离子重吸收和分泌方面发挥重要作用。
The transport of urate was evaluated in brush border membrane vesicles isolated from the dog renal cortex. It was previously shown that uphill urate and p-aminohippurate (PAH) uptake into these membrane vesicles results from imposing an outwardly directed OH- gradient. In the present study, the OH- gradient-stimulated uptake of urate was inhibited by external Cl-. In the absence of OH- gradients, imposing an outwardly directed Cl- gradient induced the transient accumulation of urate against its concentration gradient (overshoot), whereas imposing an inwardly directed Cl- gradient induced the transient uphill efflux of urate (undershoot). The effects of Cl- gradients on urate transport persisted when the diffusion potentials caused by the Cl- gradients were negated by superimposing K+ gradients in the presence of the K+ ionophore valinomycin. The dose-response curves for three different inhibitors were identical for the OH- and Cl- gradient-stimulated modes of urate uptake. The uptake of PAH was also stimulated by imposing an outwardly directed Cl- gradient. The dose-response curves for probenecid inhibition were identical for the OH- and Cl- gradient-stimulated modes of PAH uptake. Finally, the existence of a Na+ cotransport pathway for urate or PAH could not be demonstrated. We conclude that the principal mechanism for urate transport in dog renal microvillus membrane vesicles is via an anion exchanger with affinity for urate, PAH, OH-, and Cl-. This anion exchanger may play an important role in mediating organic anion reabsorption and secretion in the proximal tubule.