The Renal Excretion of Nitrogenous Compounds by the Duck (Anas Platyrhynchos) Maintained on Freshwater and on Hypertonic Saline

1969 ◽  
Vol 50 (2) ◽  
pp. 527-539
Author(s):  
D. J. STEWART ◽  
W. N. HOLMES ◽  
G. FLETCHER
Keyword(s):  
Uric Acid ◽  
Fresh Water ◽  
Hypertonic Saline ◽  
Plasma Flow ◽  
Sea Water ◽  
Renal Plasma Flow ◽  
Urea Concentration ◽  
Plasma Urea ◽  
Pah Clearance ◽  
Plasma Urea Concentration

1. The excretory rates of total nitrogen, uric acid, urea and ammonia by intact birds maintained on fresh water did not differ significantly from the corresponding rates of excretion by birds maintained on saline equivalent to 60% sea water (284 mM-NaCl, 6.0 mM-KCl). 2. The uric acid excreted by these birds contributed 53.8%, the ammonia 29.2% and the urea 1.5% of the total nitrogen excreted. The three compounds together accounted for 84.5% of the nitrogen excreted. 3. The glomerular filtration rates (inulin clearance) and the renal plasma flow rates (PAH clearance) did not differ between the freshwater-maintained and the salinemaintained birds. 4. The clearance of uric acid in all groups of birds was equal to the PAH clearance and may be interpreted as a reliable measure of the renal plasma flow rate. 5. The urea:inulin clearance ratios for the individual urine samples from all birds suggested that renal tubular synthesis and secretion of urea may occur. 6. In a second set of experiments uric acid and urea concentrations in the plasma of fed ducks were followed during adaptation to hypertonic saline and during a similar period of dehydration. 7. A sharp in the increase plasma uric acid concentration was generally observed in all groups of birds after feeding and the concentration then gradually declined to the prefeeding level. 8. The plasma urea concentrations of birds given saline equivalent to 60% sea water equilibrated, after the first 24 hr., at about twice the concentration found in the freshwater-maintained birds. 9. In birds maintained on saline equivalent to 100% sea water (470 mM-NaCl; 10 mM-KCl), the plasma urea concentration steadily rose during the first 50 hours and then equilibrated at a level approximately 10 times that observed in freshwatermaintained birds. 10. Withholding all drinking water from birds which had been previously given fresh water resulted in a rise in the plasma urea concentration during the first 50 hr. similar to that observed in the birds maintained on saline equivalent to 100% sea water. But the plasma urea concentration of these birds, in contrast to that of salinemaintained birds, continued to rise throughout the remainder of the experimental period.

The effect of dietary protein restriction on the secretory dynamics of 1α-hydroxycorticosterone and urea in the dogfish, Scyliorhinus canicula: a possible role for 1α-hydroxycorticosterone in sodium retention

1993 ◽  
Vol 138 (2) ◽  
pp. 275-282 ◽  
Author(s):  
K. J. Armour ◽  
L. B. O'Toole ◽  
N. Hazon
Keyword(s):  
Dietary Protein ◽  
Sea Water ◽  
Plasma Concentrations ◽  
Protein Restriction ◽  
Urea Concentration ◽  
Rectal Gland ◽  
Plasma Urea ◽  
Dietary Protein Restriction ◽  
Scyliorhinus Canicula ◽  
Plasma Urea Concentration

ABSTRACT The putative osmoregulatory role of the unique elasmobranch corticosteroid, 1α-hydroxycorticosterone (1α-OH-B), was investigated using dietary protein restriction as a means of limiting urea biosynthetic ability. Groups of dogfish (Scyliorhinus canicula) were adapted to either a high or a low protein diet (HPD and LPD respectively) and the secretory dynamics of urea and 1α-OH-B were determined following acclimation to normal (100%), 130% and 50% sea water. In normal sea water, LPD fish showed significantly decreased blood production of urea compared with fish fed a HPD (P <0·05), and the plasma urea concentration required to maintain iso-osmolality was achieved only by a substantial decrease in urea clearance from the plasma. Unlike HPD fish, LPD fish in 130% sea water had no apparent ability to increase plasma urea concentration. An alternative strategy adopted by these animals was the retention of high plasma concentrations of Na+ and Cl−, which increased plasma osmolality and tended to decrease osmotic water loss. Concomitant with the increased ion concentrations, plasma 1α-OH-B concentration was also greatly elevated in LPD fish indicating that the steroid may be acting to minimize Na+ (and Cl−) excretion at osmoregulatory sites such as the rectal gland, kidney and gills. This and a previous study have also demonstrated that 1α-OH-B concentration is elevated in 50% sea water. Decreases in plasma Na+ concentration are tolerated down to 75% sea water, whereafter Na+ is preferentially retained and further decreases in osmolality are achieved by reductions in plasma urea concentration. Increased 1α-OH-B concentration in 50% sea water corresponds to Na+ retention and regulation around a lower set point. The results of this study are consistent with a mineralocorticoid role for 1α-OH-B in elasmobranchs, with 1α-OH-B acting preferentially to maintain plasma Na+ concentrations under certain osmotic conditions. Journal of Endocrinology (1993) 138, 275–282

Genome-wide association for plasma urea concentration in sheep

2021 ◽  
Vol 248 ◽  
pp. 104483
Author(s):  
Taiana Cortez de Souza ◽  
Tatiana Cortez de Souza ◽  
Gregorí Alberto Rovadoscki ◽  
Luiz Lehmann Coutinho ◽  
Gerson Barreto Mourão ◽  
...  
Keyword(s):  
Urea Concentration ◽  
Genome Wide Association ◽  
Plasma Urea ◽  
Genome Wide ◽  
Plasma Urea Concentration

Urea Excretion in the Camel

1957 ◽  
Vol 188 (3) ◽  
pp. 477-484 ◽  
Author(s):  
Bodil Schmidt-Nielsen ◽  
Knut Schmidt-Nielsen ◽  
T. R. Houpt ◽  
S. A. Jarnum
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Urea Concentration ◽  
Nitrogen Excretion ◽  
Renal Tubules ◽  
Urea Clearance ◽  
Plasma Urea ◽  
Urea Excretion ◽  
Plasma Urea Concentration

The nitrogen excretion was studied in the one-humped camel, Camelus dromedarius. When a growing camel was maintained on a low N intake (dates and hay) the amount of N excreted in the form of urea, NH3 and creatinine decreased to 2–3 gm/day. This decrease was caused by a drop in urea excretion from 13 gm to 0.2–0.5 gm/day. Urea given intravenously during low N intake was not excreted but was retained. (The camel like other ruminants can utilize urea for microbial synthesis of protein.) The renal mechanism for urea excretion was investigated by measuring urea clearance and glomerular filtration rate during a period of 7 months. During normal N intake about 40% of the urea filtered in the glomeruli were excreted in the urine while during low N intake only 1–2% were excreted. The variations in urea clearance were independent of the plasma urea concentration and of glomerular filtration rate, but were related to N intake and rate of growth. No evidence of active tubular reabsorption of urea was found since the urine urea concentration at all times remained higher than the simultaneous plasma urea concentration. The findings are not in agreement with the current concept for the mechanism of urea excretion in mammals. It is concluded that the renal tubules must either vary their permeability to urea in a highly selective manner or secrete urea actively.

Residual kidney function and plasma urea concentration in patients with chronic renal failure

1990 ◽  
Vol 22 (6) ◽  
pp. 573-579 ◽  
Author(s):  
O. Schück ◽  
J. Erben ◽  
H. Nádvorníková ◽  
V. Teplan ◽  
O. Marečková ◽  
...  
Keyword(s):  
Renal Failure ◽  
Chronic Renal Failure ◽  
Kidney Function ◽  
Urea Concentration ◽  
Plasma Urea ◽  
Residual Kidney Function ◽  
Plasma Urea Concentration

Plasma Urea Concentration in Older People

1972 ◽  
Vol 14 (1) ◽  
pp. 32-35 ◽  
Author(s):  
J.S. Milne ◽  
J. Williamson
Keyword(s):  
Older People ◽  
Urea Concentration ◽  
Plasma Urea ◽  
Plasma Urea Concentration

Age-dependent blood pressure response to increased salt intake in rats influenced by a transient renal ischaemia

1986 ◽  
Vol 70 (2) ◽  
pp. 185-189 ◽  
Author(s):  
J. Kuneš ◽  
J. Jelínek ◽  
J. Zicha
Keyword(s):  
Blood Pressure ◽  
Renal Dysfunction ◽  
Renal Mass ◽  
Urea Concentration ◽  
Ischaemic Injury ◽  
Pronounced Increase ◽  
Plasma Urea ◽  
Renal Ischaemia ◽  
Salt Hypertension ◽  
Plasma Urea Concentration

1. The influence of renal dysfunction (induced by ischaemic injury) on the development of salt hypertension was studied in rats which were exposed to 60 min of renal ischaemia when either immature or adult. Saline-drinking age-matched animals served as controls. The blood pressure, plasma urea concentration, extracellular fluid volume (ECFV) and renal mass were measured 21 and 50 days after renal ischaemia. 2. Increments of plasma urea concentration and ECFV were considered to be indicators of renal dysfunction. Increased renal mass was used as an estimate of the degree of renal injury. 3. In adult rats, both plasma urea concentration and ECFV were increased 3 weeks after renal ischaemia. This correlated with a pronounced increase of renal mass. A similar relation of renal mass to ECFV was still present 50 days after renal ischaemia. 4. In rats treated when immature the increment of plasma urea concentration was much smaller and ECFV did not differ significantly from the control volumes. 5. A mild salt hypertension developed only in those rats which were treated when immature. On the other hand, the blood pressure tended to decrease in animals treated when adult. 6. It is concluded that mild renal dysfunction facilitates the development of salt hypertension in immature rats. This is in contrast with the reversed effects of extensive renal dysfunction in adult animals. 7. It is suggested that the age of animals is more important for the induction of salt hypertension than the degree of renal dysfunction.

Salvage of blood urea nitrogen in sheep is highly dependent on plasma urea concentration and the efficiency of capture within the digestive tract1,2

2007 ◽  
Vol 85 (4) ◽  
pp. 1006-1013 ◽  
Author(s):  
N. E. Sunny ◽  
S. L. Owens ◽  
R. L. Baldwin ◽  
S. W. El-Kadi ◽  
R. A. Kohn ◽  
...  
Keyword(s):  
Blood Urea Nitrogen ◽  
Urea Concentration ◽  
Urea Nitrogen ◽  
Plasma Urea ◽  
Plasma Urea Concentration

Factors affecting the urinary excretion of urea nitrogen in cattle. II. The plasma urea nitrogen concentration

1970 ◽  
Vol 21 (1) ◽  
pp. 145 ◽  
Author(s):  
RF Thornton
Keyword(s):  
Nitrogen Concentration ◽  
Urine Flow ◽  
Urea Concentration ◽  
Urea Clearance ◽  
Urea Nitrogen ◽  
Plasma Urea ◽  
Factors Affecting ◽  
Urea Excretion ◽  
Plasma Urea Concentration ◽  
Filtered Load

The relationships between the plasma urea concentration and clearance variables associated with urinary urea excretion were investigated in urea-supplemented cattle. The plasma urea concentration was related to the urinary urea output, and thus to the urea clearance and the fraction of filtered urea excreted. It is suggested that the urine flow rate was influenced by urinary urea excretion, which in turn was influenced by the plasma urea concentration and therefore by the filtered load of urea. The probable influence of the recycling of urea to the rumen on the excretion of urinary urea is discussed.

Effect of rumen degradable protein and lactation on nitrogen metabolism in dairy goats

1991 ◽  
Vol 71 (4) ◽  
pp. 1111-1124 ◽  
Author(s):  
J. Brun-Bellut ◽  
J. M. Kelly ◽  
G. W. Mathison ◽  
R. J. Christopherson
Keyword(s):  
Amino Acids ◽  
Digestive Tract ◽  
Urea Concentration ◽  
Dairy Goats ◽  
Rumen Microorganisms ◽  
Plasma Urea ◽  
Available N ◽  
Lactation Stage ◽  
Plasma Urea Concentration ◽  
Degradable Protein

Nitrogen flow and exchanges in the digestive tract were measured in three goats during a dry stage and a subsequent hormonally induced lactation stage. Two diets, formulated with and without urea to contain either a high or low level of crude protein and rumen-degradable protein (RDP), were tested in a crossover experimental design within each stage. The amount of urea nitrogen (N) recycled to the ruminoreticulum was higher (P < 0.05) during lactation (3.5 g d−1) than in the dry stage (0.9 g d−1), as was plasma urea concentration. However, the mean amount of urea recycled was lower (P < 0.05) when the high-RDP diet was fed (1.4 g N d−1) than when the low-RDP diet was fed (3.0 g N d−1), even though the plasma urea concentration tended to be higher in goats fed the high-RDP diet. Of the estimated ruminally available N, 90–110% was incorporated into microbial cells. The proportion of bacterial N derived from rumen ammonia (0.77–0.89) was not influenced by protein source or lactation. Of the amino acids flowing into the duodenum, 69–75% were apparently absorbed in the small intestine, whereas total digestive tract apparent digestibility ranged from 81 to 83%. No more than 60% of the fecal N was derived from undigested bacteria from the rumen. It was concluded that the amount of urea which is recycled to the rumen is under metabolic control and that there is efficient use of ruminally available N by rumen microorganisms. Key words: Goats, lactation, rumen-degradable protein, 15N, urea recycling, amino acids

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