Khan A H, Wilson S, Crawhall J C
Can J Physiol Pharmacol. 1975 Feb;53(1):113-9. doi: 10.1139/y75-015.
The in vitro transport of [2-14-C]uric acid, [8-14-C]hypoxanthine, and [8-14-C]xanthine, each dissolved in Krebs--Ringer bicarbonate buffer, was studied with everted jejunal sacs from rat and hamster. No evidence could be obtained for the development of a concentration gradient between the intracellular fluid and the incubation medium or between the sac contents and the incubation medium, for any of the three oxypurines. Inhibitiors of active transport, such as anaerobiosis for dinitrophenol, had no significant effect on the rate of transport. A large percentage of hypoxanthine and xanthine was oxidized to urine acid in the sac-wall homogenate, sac contents, and incubation medium during the course of the incubation. This oxidation could be prevented by addition of allopurinol (3 mM) to the incubation medium, but concentration gradients were still not obtained. No active transport mechanism could be demonstrated for uric acid, hypoxanthine, or xanthine in rat or hamster jejunum.
分别将溶解于 Krebs - Ringer 碳酸氢盐缓冲液中的[2 - 14 - C]尿酸、[8 - 14 - C]次黄嘌呤和[8 - 14 - C]黄嘌呤，用大鼠和仓鼠的外翻空肠囊进行体外转运研究。对于这三种氧嘌呤中的任何一种，均未发现细胞内液与孵育介质之间或囊内容物与孵育介质之间形成浓度梯度的证据。主动转运抑制剂，如厌氧或二硝基苯酚，对转运速率无显著影响。在孵育过程中，大部分次黄嘌呤和黄嘌呤在囊壁匀浆、囊内容物和孵育介质中被氧化为尿酸。向孵育介质中添加别嘌呤醇（3 mM）可防止这种氧化，但仍未形成浓度梯度。在大鼠或仓鼠空肠中，未证明尿酸、次黄嘌呤或黄嘌呤存在主动转运机制。
