Renal response of the starling (Sturnus ;ulgaris) to an intravenous salt load
Braun, E.J.
American Journal of Physiology 234(4): F270-F278
1978
ISSN/ISBN: 0002-9513 PMID: 645862 Document Number: 127487
Total kidney GFR under control conditions (2.5% mannitol infusion) and in starlings subjected to an osmotic stress induced by i.v. infusion of 5.8% NaCl. Under control conditions, GFR was 2.92 ml/kg per min, urine flow 0.20 ml/kg per min, 63% of filtered Na was reabsorbed, mean mammalian type (MT) SNGFR was 15.6 nl/min and mean reptilian type (RT) SNGFR was 7.0 nl/min. During osmotic stress the GFR did not change, urine flow increased to 3 times the control level, the percentage of filtered Na reabsorbed did not change, both mean MT SNGFR (24.3 nl/min) and mean RT SNGFR (10.3 nl/min) were significantly higher than control levels. During the osmotic stress more MT and fewer RT nephrons were filtering than during control conditions. Under control conditions 98.5% of the NA excreted by the kidney was associated with uric acid. This percentage decreased as osmotic stress increased. Starlings tended to excrete the osmotic load imposed by infusion of NaCl to prevent plasma osmolality from increasing.