Renal tubular transport of organic acids. Studies with oxalate and para-aminohippurate in the rat.
Renal tubular transport of organic acids. Studies with oxalate and para-aminohippurate in the rat.
复制标题
有机酸的肾小管转运。
DOI：
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发表时间：
1978
影响因子：
15.9
通讯作者：
S. Sansom
中科院分区：
文献类型：
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作者：
E. Weinman;S. J. Frankfurt;A. Ince;S. Sansom
通过自由流动显微穿刺、小管内显微注射和液滴旋进技术研究了大鼠肾脏对草酸盐的处理。持续静脉输注[（14）C]草酸盐后，近端小管早期草酸盐的递送分数为120.1+/-4.4%，表明为净分泌。晚期近端小管（124.6+/-6.1）、远端小管（120.9+/-2.9）和最终尿液（126.2+/-2.9%）的部分递送率与早期近端小管无差异。将草酸盐直接微注射到早期近曲小管和晚期近曲小管中，尿液回收率分别为85+/-3%和101+/-2%，这表明草酸盐吸收确实发生在近曲小管的中部。液滴旋进研究证实了草酸的分泌通量。与草酸盐相反，对氨基马尿酸盐（PAH），更传统的有机酸运输的标志物，分泌在近端小管的后期部分，并在很大程度上在后期近端和远端小管之间的一个网站，大概是直部。丙磺舒抑制PAH分泌，但对草酸盐净转运、草酸盐吸收或草酸盐分泌无影响。这些研究表明，净草酸的分泌发生在近曲小管的早期部分，经历双向运输的近曲小管的后来的部分，大约相等的幅度，可能是不运输在更远的肾单位网站。草酸盐的分泌机制与PAH不同，因为它位于肾单位的不同节段，不受丙磺舒抑制。这些差异表明，早期部分的近端小管是重要的肾脏代谢的一些有机酸。
The renal handling of oxalate was examined by free-flow micropuncture, intratubular microinjection, and droplet precession techniques in the rat. After the sustained i.v. infusion of [(14)C]oxalate, the fractional delivery of oxalate from the early portions of the proximal tubule was 120.1+/-4.4%, indicating net secretion. Fractional delivery rates from the late proximal tubule (124.6+/-6.1), distal tubule (120.9+/-2.9), and final urine (126.2+/-2.9%) were not different from that of the early proximal tubule. Direct intratubular microinjections of oxalate into the early proximal tubule and late proximal tubule yielded urinary recovery rates of 85+/-3% and 101+/-2%, respectively, suggesting that oxalate absorption does occur in the mid-portions of the proximal tubule. Droplet precession studies confirmed a secretory flux for oxalate. In contrast to oxalate, para-aminohippurate (PAH), the more traditional marker for organic acid transport, was secreted in the late portions of the proximal tubule and in large measure at a site between the late proximal and distal tubules, presumably the pars recta. Probenecid inhibited PAH secretion but was without effect on net oxalate transport, oxalate absorption, or oxalate secretion. These studies demonstrate that net oxalate secretion occurs in the early portions of the proximal convoluted tubule, undergoes bidirectional transport of approximately equal magnitude in later segments of the proximal tubule, and probably is not transported in more distal nephron sites. The secretory mechanism for oxalate differs from that of PAH in that it is located in a different segment of the nephron and is not inhibited by probenecid. These differences suggest that the early portions of the proximal tubule are important in the renal metabolism of some organic acids.