scholarly journals Corticomedullary Shunting After Ischaemia and Reperfusion in The Porcine Kidney?

2020 ◽  
Author(s):  
Michael Rehling ◽  
Stine Gram Skjøth ◽  
Anna Krarup Keller ◽  
Lene Elsebeth Nielsen ◽  
Christian Flø ◽  
...  
Keyword(s):  
Renal Cortex ◽  
Renal Medulla ◽  
Renal Perfusion ◽  
Visual Evaluation ◽  
Contralateral Kidney ◽  
Renal Uptake ◽  
Renal Ischaemia ◽  
Pig Kidney ◽  
Ischaemia And Reperfusion

Abstract Background: An animal model offers the opportunity to study organs in vivo and the porcine model was chosen to simulate a renal transplantation with complications. Renal perfusion may redistribute from cortex to medulla during systemic hypovolaemia and after renal ischaemia for other reasons, but there is no consensus on this matter. We studied renal perfusion after renal ischaemia and reperfusion.Methods: Renal perfusion distribution was examined by use of 153Gadolinium-labeled microspheres (MS) after 2 hours (hrs) and 4 hrs ischaemia of the pig kidney followed by 4 hrs of reperfusion. Intra-arterial injected MS are trapped in the glomeruli in renal cortex, which means that MS are not present in the medulla under normal physiological conditions.Results: Visual evaluation after reperfusion demonstrated that MS redistributed from the renal cortex to the medulla in 6 out of 16 pigs (38%) subjected to 4 hrs ischaemia and in one out of 18 pigs subjected to 2 hrs ischaemia. Central renal uptake of MS covering the medullary/total renal uptake was significantly higher in kidneys subjected to 4 hrs ischaemia compared with pigs subjected to 2 hrs ischaemia (69±5% vs. 63±1%, p<0.001), and also significantly higher than in the contralateral kidney (69±5% vs. 63±2, p<0.001). Analysis of blood and urine demonstrated no presence of radioactivity. Conclusion: The study demonstrated the presence of MS in the renal medulla in response to renal ischaemia and reperfusion suggesting that severe ischaemia and reperfusion of the pig kidney leads to opening of functional shunts bypassing glomeruli.

Vanadium, Na-K-ATPase, and potassium adaptation in the rat

1983 ◽  
Vol 244 (2) ◽  
pp. F105-F111 ◽  
Author(s):  
H. Higashino ◽  
J. D. Bogden ◽  
M. A. Lavenhar ◽  
J. W. Bauman ◽  
T. Hirotsu ◽  
...  
Keyword(s):  
Colonic Mucosa ◽  
Renal Cortex ◽  
Potent Inhibitor ◽  
Renal Medulla ◽  
Tissue Levels ◽  
Basal Activity ◽  
Potassium Adaptation ◽  
Potassium Loading

Vanadate is a potent inhibitor of Na-K-ATPase in vitro. It has been suggested that vanadium may function as a cellular regulator of Na-K-ATPase in vivo. To examine this speculation, we studied in rats the effect of high vanadate intake on 1) the tissue levels and distribution of vanadium, 2) basal activity of Na-K-ATPase in various tissues, and 3) the activity of Na-K-ATPase in various organs under conditions of massive chronic potassium loading known to stimulate Na-K-ATPase in the kidney and colon. Despite extremely high tissue levels of vanadium there was no demonstrable effect of the element on the basal activity of Na-K-ATPase. When subjected to chronic potassium loading, rats with high tissue vanadium concentrations underwent potassium adaptation that was associated with a rise in Na-K-ATPase activity in the renal cortex, renal medulla, and colonic mucosa. Further studies are needed to support or refute the thesis that vanadium might be an intracellular regulator of Na-K-ATPase in vivo.

Perfusion pressure dependency of in vivo renal tubular dynamics

1997 ◽  
Vol 273 (5) ◽  
pp. F667-F673 ◽  
Author(s):  
Martin Rodriguez-Porcel ◽  
Lilach O. Lerman ◽  
Patrick F. Sheedy ◽  
J. Carlos Romero
Keyword(s):  
Perfusion Pressure ◽  
Renal Medulla ◽  
Renal Perfusion ◽  
Sodium Reabsorption ◽  
Transit Times ◽  
Group A ◽  
Intact Kidney ◽  
Renal Tubular ◽  
Group B

To examine whether changes in renal perfusion pressure (RPP) within the range of autoregulation induce detectable changes in tubular dynamics in an entire nephron population of the intact kidney, we measured, using electron beam computed tomography (EBCT), transit times (TT, s) and intratubular concentration (%) of filterable contrast media in various nephron segments simultaneously with renal regional perfusion. In seven dogs ( group A) this was performed at the upper and lower limits of autoregulation (RPP = 130 and 95 mmHg, respectively) while group B( n = 5) served as control. In group A alone, a decrease in RPP led to an increase in TT by 40%, 68%, and 32% in the proximal tubules, ascending limb of Henle’s loop, and distal tubules, respectively, in association with an increase in intratubular concentration (+50%, 80%, and 42%, respectively). Papillary perfusion decreased, whereas perfusion of the adjacent, outlying inner medulla increased. The decrease in papillary perfusion correlated positively with the concurrent change in sodium excretion ( R = 0.81). This study demonstrates that changes in RPP within the autoregulatory range elicit changes of tubular sodium reabsorption mainly in proximal, distal, and ascending tubules, in which most of the nephrons participate. These tubular changes are associated with an alteration of perfusion circumscribed to two areas of the inner renal medulla.

Role of megalin in renal handling of aminoglycosides

2001 ◽  
Vol 281 (2) ◽  
pp. F337-F344 ◽  
Author(s):  
Junya Nagai ◽  
Hiroaki Tanaka ◽  
Naoki Nakanishi ◽  
Teruo Murakami ◽  
Mikihisa Takano
Keyword(s):  
Brush Border Membrane ◽  
Renal Cortex ◽  
Renal Medulla ◽  
Bolus Administration ◽  
Renal Tubules ◽  
Vitamin D Binding Protein ◽  
Renal Handling ◽  
Renal Brush Border Membrane

The role of megalin in tissue distribution of aminoglycosides was examined in normal rats and maleate-treated rats that shed megalin from the renal brush-border membrane. In normal rats, amikacin administered intravenously accumulated most abundantly in the renal cortex, followed by the renal medulla. No amikacin was detected in other tissues. Tissue distributions of amikacin were well correlated with megalin levels in each tissue. Bolus administration of gentamicin increased urinary excretion of megalin ligands (vitamin D binding protein and calcium), suggesting the competition between gentamicin and these megalin ligands in renal tubules. Ligand blotting showed that binding of45Ca2+ to megalin was inhibited by aminoglycosides. Both megalin levels and amikacin accumulation in renal cortex were decreased by maleate injection. Then, amikacin accumulation recovered proportionate to megalin levels. These findings suggest that megalin is involved in the renal cortical accumulation of aminoglycosides in vivo. In addition, the interaction between aminoglycosides and calcium in the kidney may be due to the competition among these compounds to bind to megalin.

scholarly journals Assessment of Perfusion and Oxygenation of the Human Renal Cortex and Medulla by Quantitative MRI during Handgrip Exercise

2018 ◽  
Vol 29 (10) ◽  
pp. 2510-2517 ◽  
Author(s):  
Bryan Thomas Haddock ◽  
Susan T. Francis ◽  
Henrik B.W. Larsson ◽  
Ulrik B. Andersen
Keyword(s):  
Renal Cortex ◽  
Transverse Relaxation Time ◽  
Renal Medulla ◽  
Renal Perfusion ◽  
Secondary Hypertension ◽  
Blood Oxygenation ◽  
Quantitative Mri ◽  
Handgrip Exercise ◽  
Significant Drop ◽  
Renal Flow

BackgroundRenal flow abnormalities are believed to play a central role in the pathogenesis of nephropathy and in primary and secondary hypertension, but are difficult to measure in humans. Handgrip exercise is known to reduce renal arterial flow (RAF) by means of increased renal sympathetic nerve activity.MethodsTo monitor medullary and cortical oxygenation under handgrip exercise–reduced perfusion, we used contrast- and radiation-free magnetic resonance imaging (MRI) to measure regional changes in renal perfusion and blood oxygenation in ten healthy normotensive individuals during handgrip exercise. We used phase-contrast MRI to measure RAF, arterial spin labeling to measure perfusion, and both changes in transverse relaxation time (T2*) and dynamic blood oxygenation level–dependent imaging to measure blood oxygenation.ResultsHandgrip exercise induced a significant decrease in RAF. In the renal medulla, this was accompanied by an increase of oxygenation (reflected by an increase in T2*) despite a significant drop in medullary perfusion; the renal cortex showed a significant decrease in both perfusion and oxygenation. We also found a significant correlation (R2=0.8) between resting systolic BP and the decrease in RAF during handgrip exercise.ConclusionsRenal MRI measurements in response to handgrip exercise were consistent with a sympathetically mediated decrease in RAF. In the renal medulla, oxygenation increased despite a reduction in perfusion, which we interpreted as the result of decreased GFR and a subsequently reduced reabsorptive workload. Our results further indicate that the renal flow response’s sensitivity to sympathetic activation is correlated with resting BP, even within a normotensive range.

scholarly journals An immunohistochemical study of aspartate, glutamate, and taurine in rat kidney.

1994 ◽  
Vol 42 (5) ◽  
pp. 621-626 ◽  
Author(s):  
N Ma ◽  
E Aoki ◽  
R Semba
Keyword(s):  
Amino Acids ◽  
Renal Cortex ◽  
Rat Kidney ◽  
Renal Medulla ◽  
Loop Of Henle ◽  
Immunoperoxidase Method ◽  
Collecting Tubules ◽  
Convoluted Tubules ◽  
Thin Portion ◽  
Intrarenal Distribution

Biochemical studies have revealed considerable amounts of free amino acids in the kidney. We examined the intrarenal distribution of three amino acids (aspartate, glutamate, and taurine) in the rat kidney with an immunoperoxidase method. In the renal cortex, all three amino acids were concentrated in the renal corpuscles and in the epithelia of the collecting tubules. Immunostaining of the collecting tubules was more intense in the principal cells than in the intercalated cells. The distal convoluted tubules were also immunostained with aspartate- and glutamate- specific antibodies but not with the taurine-specific antibody. In the renal medulla, the immunoreactivity specific for aspartate and for glutamate was similar; it was weak in the thick portion of the loop of Henle and strong in the collecting tubules. Immunoreactivity specific for taurine was restricted to regions within the epithelia of the thin portion of the loop of Henle and the collecting tubules. The significance of the accumulated amino acids as osmoregulatory agents is discussed.

scholarly journals Fate of glutamate carbon and nitrogen in isolated guinea-pig kidney-cortex tubules. Evidence for involvement of glutamate dehydrogenase in glutamine sythesis from glutamate

1980 ◽  
Vol 188 (3) ◽  
pp. 873-880 ◽  
Author(s):  
G Baverel ◽  
C Genoux ◽  
M Forissier ◽  
M Pellet
Keyword(s):  
Guinea Pig ◽  
Glutamate Dehydrogenase ◽  
Carbon Skeleton ◽  
Kidney Cortex ◽  
Glutamate Metabolism ◽  
Carbon And Nitrogen ◽  
Pig Kidney ◽  
Glutamate Concentration ◽  
Rate Limiting Step

1. The pathways and the fate of glutamate carbon and nitrogen were investigated in isolated guinea-pig kidney-cortex tubules. 2. At low glutamate concentration (1 mM), the glutamate carbon skeleton was either completely oxidized or converted into glutamine. At high glutamate concentration (5 mM), glucose, lactate and alanine were additional products of glutamate metabolism. 3. At neither concentration of glutamate was there accumulation of ammonia. 4. Nitrogen-balance calculations and the release of 14CO2 from L-[1-14C]glutamate (which gives an estimation of the flux of glutamate carbon skeleton through alpha-oxoglutarate dehydrogenase) clearly indicated that, despite the absence of ammonia accumulation, glutamate metabolism was initiated by the action of glutamate dehydrogenase and not by transamination reactions as suggested by Klahr, Schoolwerth & Bourgoignie [(1972) Am. J. Physiol. 222, 813-820] and Preuss [(1972) Am. J. Physiol. 222, 1395-1397]. Additional evidence for this was obtained by the use of (i) amino-oxyacetate, an inhibitor of transaminases, which did not decrease glutamate removal, or (ii) L-methionine DL-sulphoximine, an inhibitor of glutamine synthetase, which caused an accumulation of ammonia from glutamate. 5. Addition of NH4Cl plus glutamate caused an increase in both glutamate removal and glutamine synthesis, demonstrating that the supply of ammonia via glutamate dehydrogenase is the rate-limiting step in glutamine formation from glutamate. NH4Cl also inhibited the flux of glutamate through glutamate dehydrogenase and the formation of glucose, alanine and lactate. 6. The activities of enzymes possibly involved in the glutamate conversion into pyruvate were measured in guinea-pig renal cortex. 7. Renal arteriovenous-difference measurements revealed that in vivo the guinea-pig kidney adds glutamine and alanine to the circulating blood.

scholarly journals The effects of various anions and cations on the regulation of pyruvate dehydrogenase complex activity from pig kidney cortex

1988 ◽  
Vol 253 (3) ◽  
pp. 819-825 ◽  
Author(s):  
T Pawelczyk ◽  
R A Easom ◽  
M S Olson
Keyword(s):  
Pyruvate Dehydrogenase ◽  
Pyruvate Dehydrogenase Complex ◽  
Maximal Activity ◽  
Hill Coefficient ◽  
Kidney Cortex ◽  
Complex Activity ◽  
Pig Kidney ◽  
Constant Strength ◽  
Dehydrogenase Complex

The activity of pyruvate dehydrogenase complex (PDC) purified from pig kidney cortex was found to be affected by various uni- and bi-valent ions. At a constant strength of 0.13 M at pH 7.8, K+, Na+, Cl-, HCO3- and HPO4(2-) had significant effects on the activity of PDC: Na+, K+ and HPO4(2-) stimulated, but HCO3- and Cl- inhibited. The stimulatory effect of Na+ was mediated by a change in the Vmax. of PDC only, whereas K+ produced an increase in Vmax. and a change in the Hill coefficient (h). The extent of stimulation produced by HPO4(2-)4 on the activity of PDC was dependent on the concentrations of K+ and Na+. Both cations at concentrations higher than 40 mM partially prevented the effect of HPO4(2-)4. Cl- and HCO3- anions decreased the Vmax. of the enzyme and increased the S0.5 for pyruvate. The effects of Na+, K+, Cl-, HPO4(2-) and HCO3- on the activity of PDC were additive. In the presence of 80 mM-K+, 20 mM-Na+, 10 mM-HPO4(2-), 20 mM-Cl- and 20 mM-HCO3- the activity of PDC was increased by 30%, the S0.5 for pyruvate was increased from 75 to 158 microM and h was decreased from 1.3 to 1.1. Under these conditions and at 1.0 mM-pyruvate, the activity of PDC was 80% of the maximal activity achieved in the presence of these ions and 4.5 mM-pyruvate. The present study suggests that PDC may operate under non-saturating concentrations for substrate in vivo.

Implication of renal perfusion pressure in stroke of spontaneously hypertensive rats

1980 ◽  
Vol 238 (3) ◽  
pp. H317-H324 ◽  
Author(s):  
A. Nagaoka ◽  
A. Shino ◽  
M. Shibota
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Renal Cortex ◽  
Perfusion Pressure ◽  
Renal Perfusion ◽  
Hypertensive Rats ◽  
Cerebrovascular Lesions ◽  
Spontaneously Hypertensive ◽  
Renal Perfusion Pressure ◽  
Renal Changes ◽  
Renal Cortical Blood Flow

To elucidate the significance of hypertension associated with cerebrovascular lesions (CVL), renal perfusion pressure (RPP) was controlled by aortic clips of two different sizes in stroke-prone spontaneously hypertensive rats kept under normal or salt-loaded conditions. Tail and femoral arterial pressures (RPPs) in the mildly and severely clamped animals were reduced in proportion to the severity of the clamping. In contrast, carotid pressures in both clamped groups were significantly higher than that in the controls. Proteinuria and hyperreninemia accompanied by arteriolar changes in the renal cortex were observed in the controls prior to the onset of CVL. The renal changes were inhibited by both types of clamping. The onset of CVL was delayed by the mild clamping in salt-loaded animals, but accelerated by the severe clamping in both the normal and salt-loaded animals. Renal cortical blood flow was decreased only by the severe clamping. The results suggest that reduction in RPP and/or renal ischemia, which seems to be due to the hypertensive arteriolar changes in the renal cortex, may be related to the pathogenesis of CVL in the stroke-prone rats with or without hyperreninemia.

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