Interdependence Between Glomerular Filtration and Tubular Reabsorption in the Process of Proximal Salt and Water Turnover1

Physiology ◽  
2015 ◽  
pp. 110-120
Author(s):  
P. P. Leyssac ◽  
Ejgil Bojesen
Keyword(s):  
Glomerular Filtration ◽  
Tubular Reabsorption

Kidney Function in the Crab-Eating Frog (Rana Cancrivora)

1962 ◽  
Vol 39 (1) ◽  
pp. 167-177 ◽  
Author(s):  
KNUT SCHMIDT-NIELSEN ◽  
PING LEE
Keyword(s):  
East Asia ◽  
Glomerular Filtration ◽  
Kidney Function ◽  
Sea Water ◽  
Tubular Reabsorption ◽  
Urine Flow ◽  
South East Asia ◽  
Considerable Part ◽  
Osmotic Concentration ◽  
Full Strength

1. A study has been made of kidney function in the crab-eating frog, Rana cancrivora, of south-east Asia. 2. This frog can live in full-strength sea water; in such concentrated media its blood is slightly hypertonic to the medium, and a considerable part of the osmotic concentration is due to urea. 3. In concentrated media the excretion of urea is greatly diminished. This is not due to active tubular reabsorption of urea, but primarily to a low urine flow caused by increased tubular reabsorption of water and reduced glomerular filtration. 4. In concentrated media, as compared with dilute media, only a few percent of the filtered urea appears in the urine. 5. Osmoregulation of the crab-eating frog in sea water resembles that of elasmobranchs except in that there is no evidence of active tubular reabsorption of urea in the frog.

Renal excretion of radiofluoride in the dog

1960 ◽  
Vol 198 (4) ◽  
pp. 829-832 ◽  
Author(s):  
Curtis H. Carlson ◽  
W. D. Armstrong ◽  
Leon Singer ◽  
Lerner B. Hinshaw
Keyword(s):  
Plasma Concentration ◽  
Glomerular Filtration ◽  
Renal Excretion ◽  
Urine Volume ◽  
Urine Concentration ◽  
Tubular Reabsorption ◽  
Carrier Free ◽  
Renal Clearances ◽  
Concentration Ratios

Renal clearances of continuously infused radiofluoride were measured in 10 dogs in which a large part of the skeleton had been excluded from the system in order to produce a more constant plasma radiofluoride concentration. The results were evaluated to describe the factors of glomerular filtration and tubular reabsorption of fluoride under several conditions. The animals that received carrier-free radiofluoride infusions excreted urine with a mean radiofluoride concentration 3.4–14.5 times that of the plasma. The urine-to-plasma concentration ratios obtained with animals given a load of stable fluoride was 13.5–29.6. An increased urine volume resulted in a decreased tubular reabsorption of fluoride and the clearance was increased. Chlorothiazide increased radiofluoride excretion but decreased the urine concentration. The radiofluoride clearances were always less than the creatinine clearances but were 7.8–179 times the chloride clearances. The effect of chlorothiazide was to decrease the ratio of fluoride to chloride clearance by increasing chloride clearance more than fluoride clearance.

Renal clearance of glucose in hypothermic dogs

1959 ◽  
Vol 196 (4) ◽  
pp. 866-872 ◽  
Author(s):  
G. S. Kanter
Keyword(s):  
Renal Function ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Control Period ◽  
Urine Volume ◽  
Tubular Reabsorption ◽  
Arterial Blood ◽  
Glucose Reabsorption ◽  
Kinetics Of ◽  
Glucose Excretion

Quantitative alterations in both glomerular filtration (GFR) and tubular reabsorption of glucose, before, during and after onset of hypothermia were investigated. Urine was collected by direct cannulation of ureters and arterial blood obtained from a femoral cannula. Creatinine was used to measure GFR and glucose was analyzed by the glucose-oxidase method. During control period (rectal temp. 38°C) it was found that onlg a trace (17 ± 4 mg %) (.09 ± .02 mg/min.) of glucose spilled over into the urine. With the development of hypothermia a progressive fall in glomerular filtration rate was observed (78 ± 5 ml/min. at control rectal temp. (R.T.) to 30 ± 5 ml/min. at R.T. of 25°C). In spite of the fact that less fluid was filtered across the glomerulus, both urine volume and glucose excretion increased markedly (373 ± 122 mg %) (4.3 ± 1.9 mg/min.) at R.T. of 25°C. There is obviously a twofold effect of hypothermia on renal function, physically via the cardiovascular system resulting in a falling GFR and chemically on the tubular reabsorptive processes resulting in a decreased glucose reabsorption. To study the kinetics of this decreased glucose reabsorption, glucose Tm was investigated. It was found that control glucose Tm averaged 380 mg/min. (the E/F ratio being 52%). At 27°C R.T. the Tm was 103 mg/min. (E/F ratio being 73%).

scholarly journals Glomerular permeability is not affected by heparan sulfate glycosaminoglycan deficiency in zebrafish embryos

2019 ◽  
Vol 317 (5) ◽  
pp. F1211-F1216 ◽  
Author(s):  
Ramzi Khalil ◽  
Reshma A. Lalai ◽  
Malgorzata I. Wiweger ◽  
Cristina M. Avramut ◽  
Abraham J. Koster ◽  
...  
Keyword(s):  
Basement Membrane ◽  
Heparan Sulfate ◽  
Glomerular Filtration ◽  
Glomerular Basement Membrane ◽  
Experimental Models ◽  
Tubular Reabsorption ◽  
Glomerular Filtration Barrier ◽  
Glomerular Permeability ◽  
Tracer Injection ◽  
Filtration Barrier

Proteinuria develops when specific components in the glomerular filtration barrier have impaired function. Although the precise components involved in maintaining this barrier have not been fully identified, heparan sulfate proteoglycans are believed to play an essential role in maintaining glomerular filtration. Although in situ studies have shown that a loss of heparan sulfate glycosaminoglycans increases the permeability of the glomerular filtration barrier, recent studies using experimental models have shown that podocyte-specific deletion of heparan sulfate glycosaminoglycan assembly does not lead to proteinuria. However, tubular reabsorption of leaked proteins might have masked an increase in glomerular permeability in these models. Furthermore, not only podocytes but also glomerular endothelial cells are involved in heparan sulfate synthesis in the glomerular filtration barrier. Therefore, we investigated the effect of a global heparan sulfate glycosaminoglycan deficiency on glomerular permeability. We used a zebrafish embryo model carrying a homozygous germline mutation in the ext2 gene. Glomerular permeability was assessed with a quantitative dextran tracer injection method. In this model, we accounted for tubular reabsorption. Loss of anionic sites in the glomerular basement membrane was measured using polyethyleneimine staining. Although mutant animals had significantly fewer negatively charged areas in the glomerular basement membrane, glomerular permeability was unaffected. Moreover, heparan sulfate glycosaminoglycan-deficient embryos had morphologically intact podocyte foot processes. Glomerular filtration remains fully functional despite a global reduction of heparan sulfate.

scholarly journals P27 The juvenile pig as animal model for unraveling renal drug elimination processes in children

2019 ◽  
Vol 104 (6) ◽  
pp. e28.1-e28
Author(s):  
L Dhondt ◽  
S Croubels ◽  
P De Paepe ◽  
P De Cock ◽  
M Devreese
Keyword(s):  
Animal Model ◽  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Plasma Flow ◽  
Filtration Rate ◽  
Renal Plasma Flow ◽  
Tubular Secretion ◽  
Tubular Reabsorption ◽  
Drug Elimination ◽  
Renal Drug Elimination

BackgroundOver the years pigs were promoted as potential animal model for humans due to their high degree of anatomical and physiological similarities with humans. Gasthuys et al. demonstrated that the maturation of the kidney function in terms of the glomerular filtration rate (GFR) in growing pigs was comparable to humans, but no data are currently available on renal plasma flow, renal tubular secretion and reabsorption.1 The aim of this pilot study was to unravel the contribution of distinct renal elimination processes in juvenile pigs and to compare with reported human values.MethodsEight seven-week-old pigs were intravenously administered a single bolus of a cocktail of following renal markers: iohexol (64.7 mg/kg body weight (BW), GFR), para-aminohippuric acid (PAH, 10 mg/kg BW, effective renal plasma flow (ERPF) and anion secretion), pindolol (0.05 mg/kg BW, cation secretion) and fluconazole (0.5 mg/kg, tubular reabsorption). Plasma and urinary concentrations were determined for PAH, pindolol and fluconazole at several time points. Only plasma concentrations were assessed for iohexol. PK modelling was performed with Phoenix® WinNonlin®.ResultsThe clearance of iohexol was 97.9 ± 16.1 ml/min/m² (mean ± SD). The ERPF, calculated as the renal clearance of PAH, was 9.5 ± 2.1 ml/min/kg. These GFR and ERPF values are approximately a factor 1.3 higher than the values observed in humans, namely 63.5–75.0 mL/min/m² and 6.5 ± 2.0 mL/min/kg.2,3 The net tubular secretion of PAH was 5.4 ± 1.8 mL/min/kg, which was comparable with the values obtained in humans (5.0 ± 1.8 mL/min/kg).3 Results for cation secretion and tubular reabsorption are not yet available (to be presented at the congress).ConclusionThe net tubular secretion of PAH was comparable between the juvenile pigs and humans. The GFR and ERPF were generally a factor 1.3 higher in juvenile pigs compared to humans.ReferencesGasthuys E., et al., Postnatal maturation of the glomerular filtration rate in conventional growing piglets as potential juvenile animal model for preclinical pharmaceutical research. Frontiers in Pharmacology 2017. 8.Schwartz GJ, Furth SL. Glomerular filtration rate measurement and estimation in chronic kidney disease. Pediatric Nephrology 2007;22(11):1839–1848.Gross AS, et al., Simultaneous administration of a cocktail of markers to measure renal drug elimination pathways: absence of a pharmacokinetic interaction between fluconazole and sinistrin, p-aminohippuric acid and pindolol. British Journal of Clinical Pharmacology 2001. 51(6):547–555.Disclosure(s)This study was funded by the Special Research Fund of Ghent University (BOF16/DOC/285).

Mechanism of magnesium excretion by the chicken

1962 ◽  
Vol 202 (2) ◽  
pp. 309-312 ◽  
Author(s):  
Roscoe R. Robinson ◽  
Richard M. Portwood
Keyword(s):  
Glomerular Filtration ◽  
Tubular Reabsorption ◽  
Inulin Clearance ◽  
Magnesium Salts ◽  
Magnesium Excretion ◽  
Secretory System ◽  
Filtered Load

Urinary magnesium excretion was evaluated during the administration of magnesium salts into one leg vein of the chicken by means of the Sperber technique. Changes of magnesium excretion paralleled those of filtered load and sustained unilateral differences of magnesium excretion were not observed. Corrected magnesium-inulin clearance ratios rose to values of approximately 1.0 and remained at that level despite continuing rises of filtered load. The results indicate that magnesium excretion is determined solely by glomerular filtration and tubular reabsorption. Evidence of a tubular secretory system was not obtained.

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