Renal excretion of allantoin in rats: a micropuncture and clearance study

Free-flow micropuncture and clearance studies were performed to evaluate the transport of allantoin inthe rat kidney. Inn all studies [2-14C]uric acid and [methoxy-3H]inulin were administered. With a two-step column chromatographic technique, radiolabeled uric acid and allantoin were separated in plasma, urine, and tubular fluid, and the [2-14C]allantoin concentration was determined. Tubular fluid collections were obtained under hydropenic and control coneated animals in the control and volume-expanded states. Clearance data were obtained in oxonic acid-treated animals under the same experimental conditions. These studies indicate that allantoin is not bound to plasma protein and is, therefore, freely filterable. Neither net reabsorption nor net secretion of allantoin was evident along the length of the nephron. The bubular handling of allantoin was demonstrated to be dissociated from that of uric acid in all experimental states. No significant intrarenal production of allantoin from uric acid was observed.

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Micropuncture study of uric acid transport in rat kidney

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.228.5.1597 ◽

1975 ◽

Vol 228 (5) ◽

pp. 1597-1605 ◽

Cited By ~ 25

Author(s):

RG Abramson ◽

MF Levitt

Keyword(s):

Uric Acid ◽

Proximal Tubule ◽

Rat Kidney ◽

Chromatographic Technique ◽

Acid Transport ◽

Cent Sodium ◽

Micropuncture Study ◽

Nephron Segment ◽

Fluid Collections ◽

Column Chromatographic

Free-flow micropuncture studies were perfromed to evaluated uric acid transport in the rat kidney. In all studies (a-minus 14C) uric acid and (methoxy-3H) inulin wereadministered. A simple two-step, column-chromatographic technique was utilized to separate (2-minus 14C) uric acid from its labeled oxidation product in plasma, urine, and tubular fluid. Tubular fluid collections were obtained from the early-and late-proximal tubule under control conditions and during subsequent volume expansion induced with 0.9 per-cent sodium chloride. These studies indicate bidirectional, possible active, uric acidtransport in the proximal tubule undr control conditions, with net reabsorption evident early and net decretion apparent late in this nephron segment. In association with volumeexpansion net uric acid reabsorption and secretion both decreased. No significant nettransport was evident beyond the accessible portion of the late-proximal tubule in either experimental state.

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Use of pyrazinamide to assess renal uric acid transport in the rat: a micropuncture study

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1976.230.5.1276 ◽

1976 ◽

Vol 230 (5) ◽

pp. 1276-1283 ◽

Cited By ~ 12

Author(s):

RG Abramson ◽

MF Levitt

Keyword(s):

Uric Acid ◽

Proximal Tubule ◽

Volume Expansion ◽

Acid Transport ◽

Sodium Dependent ◽

Micropuncture Study ◽

Bidirectional Transport ◽

Fluid Collections ◽

Uniform Reduction ◽

Column Chromatographic

Free-flow micropuncture studies were performed to evaluate renal uric acid transport in control and pyrazinamide-treated rats. In all studies [2-14C]uric acid and [methoxy-3H]inulin were administered. [2-14C]uric acid was determined after column chromatographic separation from its labeled oxidation product in tubular fluid, plasma, and urine. Tubular fluid collections were obtained from the early and late proximal tubule under hydropenic conditions and from the early proximal tubule during volume expansion induced with 0.9% sodium chloride. These studies indicate that pyrazinamide, in the dose employed, provokes a uniform reduction in fractional uric acid excretion but simultaneously inhibits both net uric acid reabsorption and secretion in the early and late proximal tubule, respectively. In addition, these experiments unmasked uric acid reabsorption within the late proximal tubule and bidirectional transport beyond this nephron site. These studies also suggest at least two mechanisms for uric acid reabsorption; one sodium dependent, the other independent of sodium and water transport.

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Uric acid excretion by the rat kidney

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1975.229.3.586 ◽

1975 ◽

Vol 229 (3) ◽

pp. 586-591 ◽

Cited By ~ 6

Author(s):

MA Cook ◽

JT Adkinson ◽

WE Lassiter ◽

CW Gottschalk

Keyword(s):

Uric Acid ◽

Thin Layer ◽

Wistar Rats ◽

Renal Excretion ◽

Rat Kidney ◽

Inulin Clearance ◽

Acid Excretion ◽

Uric Acid Excretion ◽

Male Wistar Rats ◽

Layer Chromatography

The renal excretion of uric acid was studied in nondiuretic (ND) male Wistar rats and in the same animals subsequently made diuretic (D) by the infusion of hypertonic saline. Clearances of endogenous urate and of inulin, determined chemically, were compared with the simultaneous clearance of 14C infused as [6(-14)C]urate or [2(-14)C]urate. In rats infused with [6(-14)C]urate the isotope/inulin clearance ratios were 0.29 +/- 0.09 (ND) and 0.31 +/- 0.11 (D) ml/min; the simultaneous urate (chemical)/inulin ratios were 0.21 +/- 0.07 (ND) and 0.24 +/- 0.08 (D) ml/min. In rats infused with [2(-14)C]urate the isotope/inulin clearance ratios were 1.02 +/- 0.5 (ND) and 1.13 +/- 0.9 ml/min (D); the simultaneous urate (chemical)/inulin clearance ratios were much lower-0.19 +/- 0.09 (ND) and 0.32 +/- 0.19 (D) ml/min. Thin-layer chromatography of urine after [6(-14)C]urate inl uric acid. In contrast, a similar analysis of urinary radioactivity after [2(-14)C]urate infusion revealed that more than 70% of the 14C was excreted as allantoin and not as uric acid.

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Renal excretion of uric acid: Alterations during stressful underwater demolition team training.

PsycEXTRA Dataset ◽

10.1037/e434932004-001 ◽

1971 ◽

Author(s):

Leonard M. Zir ◽

Robert T. Rubin ◽

Richard H. Rahe ◽

Ransom J. Arthur

Keyword(s):

Uric Acid ◽

Renal Excretion ◽

Team Training

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Suitability of the Cyclic Voltammetry Measurements and DPPH• Spectrophotometric Assay to Determine the Antioxidant Capacity of Food-Grade Oenological Tannins

Molecules ◽

10.3390/molecules24162925 ◽

2019 ◽

Vol 24 (16) ◽

pp. 2925 ◽

Cited By ~ 7

Author(s):

Arianna Ricci ◽

Giuseppina Paola Parpinello ◽

Nemanja Teslić ◽

Paul Andrew Kilmartin ◽

Andrea Versari

Keyword(s):

Cyclic Voltammetry ◽

Colorimetric Assay ◽

Radical Scavenging ◽

Calibration Graph ◽

Spectrophotometric Assay ◽

Experimental Conditions ◽

Fast Analysis ◽

Cv Measurements ◽

And Control ◽

Analytical Approaches

Twenty commercially available oenological tannins (including hydrolysable and condensed) were assessed for their antiradical/reducing activity, comparing two analytical approaches: The 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging spectrophotometric assay and the cyclic voltammetry (CV) electrochemical method. Electrochemical measurements were performed over a −200 mV–500 mV scan range, and integrated anodic currents to 500 mV were used to build a calibration graph with (+)-catechin as a reference standard (linear range: From 0.0078 to 1 mM, R2 = 0.9887). The CV results were compared with the DPPH• assay (expressed as % of radical scavenged in time), showing high correlation due to the similarity of the chemical mechanisms underlying both methods involving polyphenolic compounds as reductants. Improved correlation was observed by increasing the incubation time with DPPH• to 24 h (R2 = 0.925), demonstrating that the spectrophotometric method requires a long-term incubation to complete the scavenging reaction when high-molecular weight tannins are involved; this constraint has been overcome by using instant CV measurements. We concluded that the CV represents a valid alternative to the DPPH• colorimetric assay, taking advantage of fast analysis and control on the experimental conditions and, because of these properties, it can assist the quality control along the supply chain.

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How Downward and Upward Comparisons on Facebook Influence Grandiose and Vulnerable Narcissists’ Self-Esteem—A Priming Study

Behavioral Sciences ◽

10.3390/bs11030039 ◽

2021 ◽

Vol 11 (3) ◽

pp. 39

Author(s):

Phillip Ozimek ◽

Hans-Werner Bierhoff ◽

Elke Rohmann

Keyword(s):

Social Networking Sites ◽

Online Survey ◽

Social Comparisons ◽

Past Research ◽

Self Esteem ◽

Self Report ◽

Control Group ◽

Experimental Conditions ◽

Vulnerable Narcissism ◽

And Control

Past research showed that social networking sites represent perfect platforms to satisfy narcissistic needs. The present study aimed to investigate how grandiose (GN) and vulnerable narcissism (VN) as well as social comparisons are associated with Facebook activity, which was measured with a self-report on three activity dimensions: Acting, Impressing, and Watching. In addition, the state self-esteem (SSE) was measured with respect to performance, social behavior, and appearance. One hundred and ten participants completed an online survey containing measures of SSE and Facebook activity and a priming procedure with three experimental conditions embedded in a social media context (upward comparison, downward comparison, and control group). Results indicated, as expected, that high VN was negatively associated with SSE on each subscale and the overall score. In addition, it was found that VN, but not GN, displayed positive associations with frequency of Facebook activities. Finally, it was proposed and confirmed that VN in interaction with the priming of downward comparisons negatively affected SSE. The conclusion drawn is that VN represents a key variable for the prediction of self-esteem as well as for the frequency of Facebook activity.

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Renal effects of nitric oxide synthesis inhibition in cirrhotic rats

AJP Regulatory Integrative and Comparative Physiology ◽

10.1152/ajpregu.1994.267.6.r1454 ◽

1994 ◽

Vol 267 (6) ◽

pp. R1454-R1460 ◽

Cited By ~ 4

Author(s):

N. M. Atucha ◽

J. Garcia-Estan ◽

A. Ramirez ◽

M. C. Perez ◽

T. Quesada ◽

...

Keyword(s):

Nitric Oxide ◽

Renal Excretion ◽

Renal Plasma Flow ◽

Tubular Reabsorption ◽

Nitric Oxide Synthesis ◽

Important Mediator ◽

Experimental Liver Cirrhosis ◽

Endogenous Nitric Oxide ◽

And Control ◽

Experimental Liver

In the present study, we have characterized the renal response to inhibition of endogenous nitric oxide (NO) synthesis [intravenous NG-nitro-L-arginine methyl ester (L-NAME) for 3 h] in anesthetized cirrhotic rats, with (ASC) and without (CIR) ascites, at doses that do not change blood pressure (BP). Administration of L-NAME induced opposite effects on water (UV) and sodium (UNaV) excretion in cirrhotic and control animals. Infusion of 1 microgram.kg-1.min-1 of L-NAME in CIR (n = 5) decreased renal plasma flow (RPF) at the end of the 3-h period, whereas UV, UNaV, and glomerular filtration rate (GFR) were unaltered. In contrast, infusion of L-NAME at 10 micrograms.kg-1.min-1 in six more CIR increased UV and UNaV significantly by the 1st h, without changes in BP or GFR, and these parameters remained elevated throughout the experiment. Infusion of 1 microgram.kg-1.min-1 in ASC (n = 6) did not change BP or GFR but significantly enhanced UV and UNaV after the 1st h. These effects were prevented by pretreatment with L-arginine (0.1 mg.kg-1.min-1) in another group of ASC infused with 1 microgram.kg-1.min-1 of L-NAME. These results indicate that, in ASC and CIR cirrhotic rats, inhibition of NO synthesis at nonpressor does improves renal excretion of sodium and water via a decrease in tubular reabsorption. NO is an important mediator of the renal excretory and hemodynamic alterations of experimental liver cirrhosis.

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Natriuresis in Rats Acutely Depleted of Chloride

Clinical Science ◽

10.1042/cs0520023 ◽

1977 ◽

Vol 52 (1) ◽

pp. 23-31

Author(s):

R. G. Luke ◽

B. T. Khanh ◽

R. D. Schmidt ◽

J. H. Galla

Keyword(s):

Sodium Bicarbonate Solution ◽

Free Water ◽

Sodium Reabsorption ◽

Urinary Flow ◽

Variable Degree ◽

Water Reabsorption ◽

Chloride Depletion ◽

Sodium Load ◽

Clearance Studies ◽

And Control

1. Acute chloride depletion, without sodium depletion, was produced in rats by a single exchange peritoneal dialysis against sodium bicarbonate solution. Blood volume was restored after dialysis by infusion of salt-free albumin, and exogenous deoxycorticosterone and antidiuretic hormone were given. 2. Clearance studies in the period (3 h) after dialysis revealed no difference in the glomerular filtration rate or in the filtered sodium load between experimental and control rats but urinary sodium concentrations and absolute and fractional sodium excretion were significantly higher in the chloride-depleted group. 3. There was also a significant kaliuresis, increased urinary flow rate and diminished free water reabsorption. Urinary bicarbonate excretion increased to a variable degree but the major rise in anion excretion was ‘unmeasured’ (Na+ + K+ — [Cl− +HCO3− +PO43-]). 4. It is postulated that chloride depletion imposes limitations on sodium reabsorption in the ascending limb of the loop of Henle.

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