Nitrogen metabolism and plasma urea concentrations in fleeceweight-selected and control Romney rams

1987 ◽  
Vol 38 (5) ◽  
pp. 917 ◽  
Author(s):  
SN McCutcheon ◽  
DDS Mackenzie ◽  
HT Blair
Keyword(s):  
Creatinine Clearance ◽  
Clearance Rate ◽  
Urine Output ◽  
Plasma Concentrations ◽  
Nitrogen Retention ◽  
Urea Concentration ◽  
Plasma Urea ◽  
Plasma Urea Concentration ◽  
And Control ◽  
Daily Period

Nitrogen retention and plasma urea concentrations were examined in 2-year-old Romney rams from fleeceweight-selection and control lines. In four experimental periods rams were fed chaffed lucerne hay (110% of maintenance energy requirements) three times daily (Period I), twelve times daily (Period II), twice daily (Period IV), or were fasted (Period 111). Nitrogen balance was measured in Period I, while plasma concentrations, urinary excretions and clearances of urea and creatinine were examined in Periods II-IV. Water intake and urine output were measured in all periods. Plasma urea concentrations were also measured in the same rams at grazing. Differences between the lines in water intake, urine output, faecal and urinary nitrogen excretion and nitrogen retention were not significant. Control rams maintained significantly higher plasma concentrations of urea and creatinine than fleeceweight-selected rams but only under controlled feeding conditions (particularly twelve times daily feeding). Differences between the lines in plasma urea concentration could be accounted for by the (non-significantly) greater urinary urea excretion, and lower creatinine clearance rate, of control rams. Measurement of plasma urea concentration in sheep may provide a useful predictor of genetic merit for fleeceweight. However, it will be necessary to measure plasma urea concentration under controlled feeding conditions to accurately rank animals. Concurrent measurement of creatinine clearance rate and urinary urea excretion should also enhance the accuracy of prediction of genetic merit.

Salinity Adaptation in the Salamander Batrachoseps

1978 ◽  
Vol 76 (1) ◽  
pp. 1-10
Author(s):  
RONALD M. JONES ◽  
STANLEY S. HILLMAN
Keyword(s):  
Tap Water ◽  
Plasma Concentrations ◽  
Urea Concentration ◽  
Short Term ◽  
Osmotic Concentration ◽  
Plasma Urea ◽  
Sucrose Solutions ◽  
Urine Production ◽  
Plasma Urea Concentration

(1) Batrachoseps attenuatus and B. major were successfully acclimated to 600 m-osmol NaCl and 400 m-osmol sucrose solutions. (2) Accumulation of sodium and an increased rate of synthesis of urea provide substantial increases in plasma concentrations of these solutes. Sodium concentrations in excess of 230 mM and urea concentrations in excess of 200 mM indicate that these are the two major solutes (plus anions) responsible for elevation of osmotic concentration in Batrachoseps. (3) Batrachoseps exhibits a water balance response upon dehydration (greater than twofold increase in cutaneous uptake, 50% reduction in urine production). Urine production, estimated from bladder contents, was significantly reduced in salamanders acclimated to sucrose solutions compared to animals acclimated to tap water or saline of equivalent osmotic concentration. (4) Plasma urea concentration was equivalent to urine urea concentration when Batrachoseps was kept in tap water and during short term saline acclimation. After long term saline acclimation, urine urea concentration was one-fourth the plasma urea concentration.

scholarly journals Whole body Kt/V from dialysate urea measurements during hemodialysis.

1998 ◽  
Vol 9 (11) ◽  
pp. 2118-2123
Author(s):  
J Sternby
Keyword(s):  
Removal Rate ◽  
Plasma Concentrations ◽  
The Body ◽  
Urea Concentration ◽  
Whole Body ◽  
Water Volume ◽  
Dialysis Dose ◽  
Plasma Urea ◽  
Urea Distribution Volume ◽  
Plasma Urea Concentration

A new method for the calculation of dialysis dose from continuous measurements of dialysate urea concentrations has been developed. It is based on urea mass in the patient instead of plasma concentrations, and results in a measure of dialysis dose that has been named whole body Kt/V. The measured urea mass removal rate and the slope of the dialysate urea concentration curve are the key parameters needed for the calculations. No assumptions have to be made about urea distribution in the body (single or double pool, etc.). Blood sampling is not needed. This simplifies the logistics and eliminates the problems with rebound and timing in taking samples. The total urea mass present in the body before treatment is also obtained. It can be used directly, or in relation to body weight or water volume, as a measure of the level of urea in the body. This may serve as an alternative to pretreatment plasma concentration. If a pretreatment plasma urea concentration is available, the urea distribution volume can be calculated, which may be of separate clinical interest.

The effect of selection for fleece weight upon urea metabolism and digestive function in Romney sheep

1989 ◽  
Vol 40 (5) ◽  
pp. 1065 ◽  
Author(s):  
BC Thompson ◽  
DW Dellow ◽  
TN Barry
Keyword(s):  
Creatinine Clearance ◽  
Clearance Rate ◽  
Genetic Selection ◽  
Plasma Urea ◽  
Voluntary Feed Intake ◽  
Outflow Rate ◽  
Urea Metabolism ◽  
Selection For ◽  
Fleece Weight ◽  
Plasma Urea Concentration

The effect of 30 years genetic selection for greasy fleece weight upon rumen metabolism, apparent digestibility and nitrogen metabolism was investigated in Romney sheep.Fleece weight (Fwt) animals had a 1 mM lower plasma urea concentration than control (C) animals when fed on both diets given, but there was no difference in plasma urea IRL, urinary urea excretion or urea recycling to the digestive tract between the Fwt and C sheep when fed either diet. Relative to the C shccp, the Fwt animals had a higher creatinine clearance rate when fed the meadow hay diet, and a higher urea clearance rate when fed both diets.When fed the meadow hay diet there were no differences between the Fwt and C animals in voluntary feed intake (VFI) or apparent DM digestibility. However, when fed on the lucerne chaff diet the Fwt animals had a higher VFI than the C animals and a lower apparent DM digestibility. These changes were associated with an increase in the rumen fractional outflow rate (FOR) of lignin in the Fwt sheep, and a higher molar proportion of acetate and a lower proportion of propionate in rumen fluid.The differences in urea and creatinine clearance rates suggest that selection for fleece production may have altered kidney function, with expression of this and rumen FOR being related to nutritional level. A factor contributing to the superior wool production of the Fwt sheep is suggested.

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.

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