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

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

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

Australian Journal of Agricultural Research ◽

10.1071/ar9870917 ◽

1987 ◽

Vol 38 (5) ◽

pp. 917 ◽

Cited By ~ 14

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.

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

Journal of Experimental Biology ◽

10.1242/jeb.50.2.527 ◽

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.

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Salinity Adaptation in the Salamander Batrachoseps

Journal of Experimental Biology ◽

10.1242/jeb.76.1.1 ◽

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.

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

Journal of the American Society of Nephrology ◽

10.1681/asn.v9112118 ◽

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.

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Role of FGF21 and GCN2 in mediating the metabolic response to dietary protein restriction

Diabetologie und Stoffwechsel ◽

10.1055/s-0036-1580771 ◽

2016 ◽

Vol 11 (S 01) ◽

Author(s):

T Laeger ◽

DC Albarado ◽

L Trosclair ◽

J Hedgepeth ◽

CD Morrison

Keyword(s):

Dietary Protein ◽

Metabolic Response ◽

Protein Restriction ◽

Dietary Protein Restriction

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Neuronal FGF-21 Signaling–A Sensor of Dietary Protein Restriction

Diabetes ◽

10.2337/db18-261-lb ◽

2018 ◽

Vol 67 (Supplement 1) ◽

pp. 261-LB

Author(s):

CRISTAL M. HILL ◽

MADELEINE V. DEHNER ◽

DAVID MCDOUGAL ◽

HANS-RUDOLF BERTHOUD ◽

HEIKE MUENZBERG ◽

...

Keyword(s):

Dietary Protein ◽

Protein Restriction ◽

Dietary Protein Restriction

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238-LB: Dietary Protein Restriction Induces Myocardial Dysfunction Despite Reducing Body Weight in Aged C57BL/6J Mice

Diabetes ◽

10.2337/db20-238-lb ◽

2020 ◽

Vol 69 (Supplement 1) ◽

pp. 238-LB

Author(s):

CHRISTOPHER L. AXELROD ◽

WAGNER S. DANTAS ◽

GANGARAO DAVULURI ◽

WILLIAM T. KING ◽

CRISTAL M. HILL ◽

...

Keyword(s):

Body Weight ◽

Dietary Protein ◽

Myocardial Dysfunction ◽

Protein Restriction ◽

Dietary Protein Restriction

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Genome-wide association for plasma urea concentration in sheep

Livestock Science ◽

10.1016/j.livsci.2021.104483 ◽

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

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The Role of Reduced Methionine in Mediating the Metabolic Responses to Protein Restriction Using Different Sources of Protein

Nutrients ◽

10.3390/nu13082609 ◽

2021 ◽

Vol 13 (8) ◽

pp. 2609

Author(s):

Han Fang ◽

Kirsten P. Stone ◽

Sujoy Ghosh ◽

Laura A. Forney ◽

Thomas W. Gettys

Keyword(s):

Amino Acids ◽

Dietary Protein ◽

Target Genes ◽

Protein Restriction ◽

Metabolic Phenotype ◽

Sulfur Amino Acids ◽

Transcriptional Responses ◽

Similar Reduction ◽

Dietary Protein Restriction ◽

Methionine Restriction

Dietary protein restriction and dietary methionine restriction (MR) produce a comparable series of behavioral, physiological, biochemical, and transcriptional responses. Both dietary regimens produce a similar reduction in intake of sulfur amino acids (e.g., methionine and cystine), and both diets increase expression and release of hepatic FGF21. Given that FGF21 is an essential mediator of the metabolic phenotype produced by both diets, an important unresolved question is whether dietary protein restriction represents de facto methionine restriction. Using diets formulated from either casein or soy protein with matched reductions in sulfur amino acids, we compared the ability of the respective diets to recapitulate the metabolic phenotype produced by methionine restriction using elemental diets. Although the soy-based control diets supported faster growth compared to casein-based control diets, casein-based protein restriction and soy-based protein restriction produced comparable reductions in body weight and fat deposition, and similar increases in energy intake, energy expenditure, and water intake. In addition, the prototypical effects of dietary MR on hepatic and adipose tissue target genes were similarly regulated by casein- and soy-based protein restriction. The present findings support the feasibility of using restricted intake of diets from various protein sources to produce therapeutically effective implementation of dietary methionine restriction.

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