Urinary NH3 Research Articles

Male Kidney‐specific Bmal1 Knockout Mice Show a Similar, Exaggerated Active‐Inactive Period Difference in Ammonia Excretion to Controls after Potassium Deprivation

The influence of the circadian clock is manifested in the time‐of‐day variation in commonly recognized renal function parameters such as blood pressure and sodium excretion. Acid‐base balance is another important component of renal function, however the effect of the circadian clock on the diurnal variation of acid excretion, specifically the excretion of ammonia (NH3), has not yet been determined. We used a kidney‐specific Bmal1 knockout mouse model (KS‐Bmal1KO) created by crossing a distal nephron‐specific Ksp‐cadherin cre mouse with mice containing two loxP sites flanking exon 8 of the Bmal1 gene. Based on differences our lab has seen in the expression of genes related to acid‐base homeostasis between KS‐Bmal1KO mice and their littermate Cre‐ controls (CNTL), we hypothesized that there would be genotype differences in urinary NH3 excretion. Male control and KS‐Bmal1KO mice were placed in metabolic cages and had their urine collected in 12‐hour intervals, spanning the active (6pm‐6am) or inactive (6am‐6pm) periods. After three days on a normal potassium (K+) diet, the mice were switched to a nominally potassium‐free (0 K+) diet for five days with free access to water. Urine samples from the last two time points of the normal K+ and 0 K+ diets were analyzed for NH3. Under a normal K+ diet, CNTL mice displayed a significant time‐of‐day difference in urinary NH3 excretion, with values greater during the active period compared to the inactive period (66 ± 10 vs. 19 ± 5 μmol/12hr NH3, n=5, P<.05). KS‐Bmal1KO exhibited a similar pattern on normal K+, excreting more NH3 during the active period (78 ± 3 vs. 16 ± 3 μmol/12hr NH3, n=5, P<.05). After five days on the 0 K+ diet, the active‐inactive (A‐I) difference of NH3 excretion was exacerbated in CNTL mice, resulting in a significantly greater difference compared to normal K+diet (137 ± 15 vs. 47 ± 10 μmol/12hr NH3 P<0.05). KS‐Bma11KO mice also displayed an increased A‐I difference compared to their normal K+ diet values (142 ± 33 vs. 62 ± 5 μmol/12hr NH3, P<0.05). There were no differences however, in the A‐I difference between genotypes. Despite not observing any major effects of Bmal1 deletion in the distal nephron of the kidney on NH3 excretion under the conditions tested, these results suggest that the time‐of‐day differences in NH3 excretion observed in male mice are augmented in response to dietary K+ deprivation.Support or Funding InformationThis research was supported in part by the research project grant on Per1 and the Kidney Clock in Hypertension (NIH grant DK109570‐02), and the T32 training grant on Pre‐ and Postdoctoral Training in Nephrology and Hypertension (T32 DK104721).This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Effect of feeding sweet-potato condensed distillers solubles on intake and urinary excretion of minerals in Japanese Black steers.

Four Japanese Black steers (16 months of age) were assigned to a 4 × 4 Latin square design to investigate the effect of graded levels of sweet-potato condensed distillers solubles (SCDS) in their diets on intake and urinary excretion of minerals. The four diets consisted of 0%, 10%, 20% and 30% (dry matter (DM) basis) SCDS, with SCDS replacing commercial concentrate (CC). Intake of K, Cl, S, P and Mg increased linearly with increasing SCDS content. Urinary pH increased linearly with increasing dietary SCDS content. SCDS feeding increased urinary K concentrations (linear and quadratic effects). Urinary concentrations of Cl increased linearly with increasing SCDS content. In contrast, urinary concentrations of Mg decreased with increasing SCDS content. Feeding of SCDS did not apparently affect urinary NH3 ,P, Na or Ca concentrations. These results suggest that high SCDS feeding is not a risk for crystallization of minerals leading to the formation of magnesium-phosphate type calculi: although SCDS contains large amounts of P and Mg, high SCDS feeding decreased the Mg concentration and did not affect the P concentration in urine. Additionally, high SCDS feeding had no apparent effects on plasma concentrations of Na, K, Cl, Ca or inorganic P.

The effect of acidosis on the labelling of urinary ammonia during infusion of [amide-15N]glutamine in human subjects.

In three experiments [amide-15N]glutamine was infused intravenously in male volunteers. After 4-8 h of infusion acidosis was achieved by an oral dose of CaCl2 (1 mmol/kg). In one subject acidosis was maintained for 5 d. The acid load produced an approximately 3-fold increase in urinary NH3 excretion, with a small (approximately 20%) and transient increase in the isotope abundance of urinary NH3. Estimates of glutamine production rate (flux) were obtained in two experiments. There was no evidence that it was increased in acidosis. The extra NH3 production by the kidney represented only a very small part, about 3%, of the total glutamine production rate.

Alteration of nitrogen metabolism by alpha-ketoglutarate administration in growing lambs fed high nonprotein nitrogen-containing diets.

Two completely randomized design experiments were conducted, using either 10, 38-kg (Exp. 1) or 10, 26-kg (Exp. 2) Hampshire x Western wether lambs, to study the effects of alpha-ketoglutarate (AKG) administration on N metabolism. Lambs were fed 890 and 885 g DM/d in Exp. 1 and 2, respectively, of corn-cottonseed hull basal diets with urea added to attain CP levels of 10.6 and 10.5% in Exp. 1 and 2, respectively. Experiments consisted of 10 d of adaptation followed by 7 d of infusion and excreta collection. Lambs were infused continuously either i.v. (Exp. 1) or abomasally (Exp. 2) with control solutions (CON) or solutions containing 41.3 g AKG/d (AKG). In Exp. 1, fecal and urinary N excretion and N retention were not affected (P greater than .10) by treatment. Compared to CON in Exp. 2, AKG infusion increased (P less than .10) fecal N output (6.6 vs 5.9 g N/d) but did not affect (P greater than .10) the amount of N retained (4.4 vs 3.5 g N/d). Compared to CON, AKG increased (P less than .10) urinary NH3 N excretion in Exp. 1. Serum urea N was lower (P greater than .10) for AKG than for CON in Exp. 1 but was not affected (P greater than .10) by treatment in Exp. 2. In Exp. 1, AKG appeared to reduce activities of several serum enzymes that function in amino N metabolism. In Exp. 1, compared to CON, AKG decreased (P less than .10) aspartate but increased (P less than .10) asparagine in serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Nitrate biosynthesis in the rat. Precursor-product relationships with respect to ammonia.

The endogenous biosynthesis of nitrate in rats was investigated by using 15NH3 administered as a continuous intravenous infusion for as long as 96 h. A comparison of the enrichment of 15N in urinary nitrate after a 24 h infusion revealed that it was 36% of the enrichment of plasma NH3 and about 50% of the enrichment of plasma urea and urinary NH3. Continuous infusion of 15NH3 for 96 h showed that a plateau for the incorporation of NH3 into nitrate is reached by 24 h, whereas the enrichment of urinary NH3 and urea increase during the 96 h. After the infusion of progressively larger doses of 15NH3, the concentration of nitrate synthesized de novo increased. Although there was a significant correlation between plasma 15NH3 concentration and 15NO3- appearance, a given change in plasma NH3 concentration does not produce a direct proportional change in nitrate synthesis. Our findings indicate that NH3 is a quantitatively significant nitrogen precursor for nitrate, but that approx. 50% of nitrate nitrogen is derived from other, as yet unidentified, sources.

The combined effects of infection and malnutrition on protein metabolism in children.

Twenty-two children were studied as inpatients at a Nigerian Hospital. They were divided into four groups on the basis of weight for age: I, adequately nourished, acutely infected; II, moderately under weight, acutely infected; III, malnourished, chronically infected; IV, malnourished, uninfected. Urinary nitrogen excretion was highest in group I and lowest in groups III and IV. Urinary creatinine was highest in group I, but did not differ significantly in groups II, III and IV. The excretion of 3-methylhistidine closely paralleled that of creatinine. It is suggested that the high rates of creatinine and methylhistidine excretion in group I resulted in part from destruction of muscle. Rates of whole body protein turnover were measured by administration of a single dose of [15N]glycine with measurement of the excretion of 15N in urinary NH3 for the next 9 h. Rates of protein synthesis and breakdown were very high in infected children of groups I and II. Although rates were lower in the malnourished groups, in infected children of group III they were nearly twice as high as in the uninfected group IV. The net balance of protein (synthesis minus breakdown) was negative in group I, less negative in group II, zero in group III and positive in group IV. Repeat measurements in group I during recovery from infection showed a decline in rates of excretion of nitrogen, creatinine and 3-methylhistidine. Rates of protein synthesis and breakdown declined and the protein balance became less negative, but these changes were not statistically significant. Multiple regression analysis of the results of all groups taken together showed independent contributions to rates of protein metabolism from infection and nutritional state, especially plasma albumin. It was concluded that infection caused a rise in protein breakdown which was larger than the concomitant rise in synthesis, leading to net loss of protein, and that these responses were reduced by malnutrition.

Source and function of urinary ammonia in the alligator

The rate of renal deamination of 18 amino acids was determined by injecting them into alligators and measuring the ammonia excreted. Not only did glycine, alanine, glutamine and leucine account for nearly half of the plasma amino acids, they were also deaminated more rapidly than any of the others. In view of this it was concluded that these four amino acids are the natural precursors of urinary NH3 in the alligator. Increased NH3 and CO2 excretion following glycine injections resulted in increased renal reabsorption of Na and Cl when NaCl was injected and increased Na reabsorption when NaHCO3 or Na phosphate solutions were injected. The fact that excess NH4HCO3 excretion enhances salt reabsorption independent of plasma pH makes it probable that the excretion of N is the chief function of the ammonia mechanism and that salt conservation is incidental. Insulin decreased the plasma amino acid level and drastically reduced the NH3 excretion. With the decrease in ammonia, NaCl and NaHCO3 were excreted in increased amounts.

Renal excretion of carbon dioxide and ammonia by the alligator.

SummaryThe NH3 and C02 produced by the kidney in normal well hydrated alligators accounts for over 2/3 of the osmotic pressure of the urine. Since the volume of urine required to excrete the non-volatile cations and anions is normally low, NH3 and CO2 production by the kidney appears to have a diuretic function. In dehydration, NH3 and CO2 production decreases, but the quantity of extracellular electrolytes excreted remains essentially the same as in well hydrated animals. Ammonia and CO2 also function in acid and base conservation. In inorganic anion excretion, CO2 production is decreased, whereas in cation excretion NH3 production is decreased. Due to the urine “osmolar ceiling” NH3 and CO2 are decreased to “make room” for any injected cations and anions. Hydration or the injection of non-osmotic diuretics appears to be the only stimulus to increased NH3 and CO2 production, the blood or urine pH playing no detectable part in this mechanism. Since the greatest amount of urinary NH3 appears in well hydrat...