Anderson G L, Braun E J
Am J Physiol. 1985 Jan;248(1 Pt 2):R93-8. doi: 10.1152/ajpregu.1985.248.1.R93.
The role of the cloaca and lower intestine in the postrenal modification of urine was studied in conscious normally hydrated desert quail. The birds were studied for a period of 12 days during which they were in intake-output balance. It was calculated that of the combined mixture of urine-feces entering the lower intestine, 47% water, 62% sodium, and 49% potassium were reabsorbed. If this material is considered as coming from the ureteral urine, then the composition of the ureteral urine entering the lower intestine was changed as follows: 77% water, 72% sodium, and 82% potassium were reabsorbed. For urate, 68% of the total present in ureteral urine was degraded in the lower intestine. In terms of the filtered load produced by the kidneys, the lower intestine reabsorbed 1.5% filtered water, 0.4% filtered sodium, and 46% filtered potassium. The total filtered loads reabsorbed by the combined efforts of the kidney and lower intestine were 99.5% water, 99.8% sodium, and 88% potassium. It appears that the cloaca and lower intestine of birds may serve a similar function to that of the distal nephron in mammals, making the fine adjustments in water and sodium reabsorption from the urine.
在清醒且水分正常的沙漠鹌鹑中，研究了泄殖腔和下肠道在肾后尿液修饰中的作用。对这些鸟类进行了为期12天的研究，在此期间它们处于摄入-排出平衡状态。经计算，进入下肠道的尿-粪混合物质中，47%的水、62%的钠和49%的钾被重吸收。如果将该物质视为来自输尿管尿液，那么进入下肠道的输尿管尿液组成变化如下：77%的水、72%的钠和82%的钾被重吸收。对于尿酸盐，输尿管尿液中总含量的68%在下肠道中降解。就肾脏产生的滤过量而言，下肠道重吸收了1.5%的滤过水、0.4%的滤过钠和46%的滤过钾。肾脏和下肠道共同作用重吸收的总滤过量为99.5%的水、99.8%的钠和88%的钾。看来鸟类的泄殖腔和下肠道可能具有与哺乳动物远端肾单位类似的功能，对尿液中的水和钠重吸收进行精细调节。
