title: Postrenal modification of urine in birds.
abstract: 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.
mesh_terms: D000042:Absorption; D000818:Animals; D002988:Cloaca / Q000378:metabolism*; D007413:Intestinal Mucosa / Q000378:metabolism*; D011188:Potassium / Q000652:urine; D011784:Quail / Q000652:urine*; D012964:Sodium / Q000652:urine; D014527:Uric Acid / Q000652:urine
chemical_list: D014527:Uric Acid; D012964:Sodium; D011188:Potassium