bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimation of Superficial Nephron Pars Recta Sodium Reabsorption in vivo
Authors: Reineck John
Published: November 2008

Many in vitro studies have examined the transport characteristics of the pars recta. Yet, because this nephron segment is inaccessible to direct micropuncture, its in vivo reabsorptive capacity remains unknown. In superficial nephrons, water movement between the late proximal and early distal tubule is limited to the pars recta and thin descending limb of Henle’s loop. Net water reabsorption in this latter segment is dependent on a favorable osmotic gradient generated by the hypertonic medullary interstitium. Accordingly, if this hypertonicity is abolished, net water movement between the late proximal and early distal tubule is limited to the pars recta. Since sodium reabsorption is isotonic along the pars recta, a comparison of fractional water delivery to the late proximal and early distal tubule provides an index of sodium reabsorption by this nephron segment. Therefore, furosemide was administered to 7 Munich-Wistar rats and micropuncture samples were obtained from the late proximal and early distal tubules. Ascending vasa recta (AVR) samples were also obtained and the ratio of AVR/plasma osmolality were determined and averaged 1.04, indicating that furosemide abolished medullary hypertonicity. The fractional delivery of filtrate to the late proximal tubule averaged 40.2% and that to the early distal tubule 30.0%, indicating that 10.2% of the filtered sodium was re-absorpbed along the pars recta. The administration of benzolamide, a carbonic anhydrase inhibitor, decreased this value to 5% of the filtered load.
Comparison of the Chemical and Polypeptide Composition of Tubular and Glomerular Basement Membranes
Authors: Butkowski Ralph J. , Grantham Jared J. , Hudson Billy G.
Published: November 2008

Renal tubular and glomerular basement membranes were isolated from rabbit, rat and mouse kidneys. Methods were developed to obtain the basement membrane from limited numbers of animals. Rabbit and mouse tubular basement membrane as well as rabbit and rat glomerular basement membrane were obtained from single animals in quantities sufficient for electrophoresis and chemical analysis. The chemical composition of all the basement membranes were compared and sodium dodecylsulfate-polyacrylamide gel electrophoresis was performed on rabbit tubular and glomerular basement membranes in order to compare their polypeptide composition. The chemical composition of the tubular basement membranes were similar, each species having nearly equal concentrations of glycine, hydroxyproline and hydroxylysine, respectively. Glomerular basement membranes were also similar to each other and close to tubular basement membranes in chemical composition. Within each species, the glycine, hydroxyproline and hydroxylysine values for tubular basement membrane were about 10% higher than for glomerular basement membrane. The polypeptide composition of a reduced, sodium dodecylsulfate-soluble fraction of the rabbit basement membranes appeared to be alike with two exceptions. A prominent band of Mr = 160,000 seen in gels of tubular basement membrane was present as a lightly staining band in glomerular basement membrane samples and a prominent band of Mr = 140,000 in gels of glomerular basement membrane was seen as a light band in samples of tubular basement membrane.
The Role of Visceral Epithelial, Endothelial and Mesangial Cells in the Formation and Turnover of Glomerular Basement Membrane
Authors: Nayyar Rajinder P. , Volini Frederick I. , Borke James L.
Published: November 2008

Incorporation of 3H-proline in the mouse kidney was studied by electron microscopic radioautography in a pulse-chase mode to establish the role of visceral epithelial, endothelial, and mesangial elements in the synthesis and turnover of glomerular basement membrane. Visceral epithelial and endothelial cells were found to play a significant role in the formation of glomerular basement membrane components, and turnover time for one of the components was found to be under 2 h. The synthesis of second component is slow and may take 8–24 h. The mesangial cells appear to play a significant role in the reabsorption of the component with a faster turnover rate.
Glomerular Filtration Barrier in Aminoglycoside-Induced Nephrotoxic Acute Renal Failure
Authors: Luft F.C. , Evan A.P.
Published: November 2008

To elucidate the role of the glomerular filtration barrier in the development of nephrotoxic acute renal failure, we produced acute renal failure in rats with either gentamicin or tobramycin. Both drugs evoked changes in the glomerular capillary endothelium. Gentamicin administration resulted in a dose-related decrease in the diameter, density and area of endothelial fenestrae, which was considerably more pronounced than those observed with tobramycin. Prolonged, high-dose gentamicin administration caused a decrease in creatinine clearance, an increase in plasma renin activity and a corresponding decrease in the area available for filtration. These changes reverted with continued drug administration. These results support the notion that morphological alterations in the filtration barrier are responsible for the decrease in filtration observed in acute renal failure. The changes may be at least in part mediated by the renin-angiotensin system.
Macrophages in NZB/NZW Mouse Glomerular Disease
Authors: Hunt J.S. , McGiven A.R. , Jackson Anne E. , Day W.A.
Published: November 2008

Glomerular cultures from mice have been established and the various cells associated with them observed microscopically by phase contrast time-lapse cinematography, after histological staining and ultrastructurally with the transmission and scanning electron microscope. The most common cell types were large 80–200 µm diameter irregular polyhedral cells appearing as flattened plate-like structures morphologically, possibly of epithelial origin. Smaller 70–100 µm diameter fusiform cells possibly derived from either endothelium or mesangium were also often seen. A third cell type, small 10–20 µm diameter circular, motile and actively phagocytic was especially noticeable in cultures of hybrid New Zealand Black/New Zealand White mice but was not present in appreciable numbers in control cultures from strains without renal disease. This third cell type appeared to have Fc receptors, stained positively with non-specific esterase and by indirect immunofluorescence with specific rabbit anti-mouse macrophage serum and had the morphological appearance of a macrophage by scanning and transmission electron microscopy. It is concluded that cells of macrophage origin are associated with the immune complex glomerulonephritis in these hybrid mice.
Glomerular Basement Membrane Changes in Hereditary Glomerular Diseases
Authors: Gubler M.C. , Levy M. , Naizot C. , Habib R.
Published: November 2008

Ultrastructural glomerular basement membrane changes are present in most hereditary glomerular diseases: thick and thin basement membrane with splitting of the lamina densa in Alport’s syndrome, thin basement membrane in familial benign essential hematuria, and thick basement membrane with the presence of collagen-like fibrils in the nail-patella syndrome. They are useful markers for diagnosis. Moreover, their knowledge has set the problem of the primary biochemical defect in basement membrane metabolism accounting for morphological abnormalities and clinical disturbances. Further biochemical and immunochemical investigations are still required for a better understanding of hereditary glomerular diseases.
Glomerular Basement Membrane: Its Antigenicity Evaluated by Antistreptococcal Cell Membrane Antisera
Authors: Lange C.F.
Published: November 2008

Rabbit antistreptococcal membrane antisera have been demonstrated to crossreact with both human and mouse glomerular basement membrane (GBM). Though some antisera may display broad antimammalian tissue, specificity select sera were found that were specific for the GBM. The antigenicity of the GBM was also shown to change with age where certain antisera reacted with adult tissue but not with young and vice versa. Two key periods were demonstrated, one starting at about 10 days and another at about 3 months. One in vitro, indirect fluorescent antibody testing the young tissue (10–20 days) was often more reactive than older tissue. By in vivo testing these same antisera showed greater activity in animals older than 3 months. These results establish that these antisera may serve as a vital adjunct to all antisera for recognition of specific GBM antigens.
Basement Membranes: Structure Function Relationships
Authors: Kefalides Nicholas A.
Published: November 2008

Basement membranes perform several functions including filtration and elastic support. In the glomerular capillary two regions of extracellular matrix are recognized: the laminae rarae and the lamina densa. Procollagen and noncollagen glycoproteins occupy the laminae rarae and lamina densa. Proteoglycans are present in the laminae rarae. The nature and spatial organization of the macromolecules within the basement membrane determine their filtration and elastic properties. The persistence of the procollagen molecules assures the low order of fibril organization and permits selective filtration, whereas the persistence of the noncollagen extension peptides in the procollagen and the presence of the glycoproteins confers elasticity. The anionic nature of basement membranes is determined primarily by the acidic amino acid content and to much lesser extent by sialic acid and proteoglycans.
Chemical Characterization and Functional Role of Human Glomerular Basement Membrane Components
Authors: Gerfaux Jacqueline , Lanson Monique , Chany-Fournier Françoise
Published: November 2008

Sub fractions of human glomerular basement membrane isolated by enzymatic procedures were analyzed for their chemical structure and biological activity. Pepsin or collagenase digestion of purified basement membranes released three groups of components: collagenous and noncollagenous fractions and also a mixed material consisting of a proteolysis-resistant association between collagen sequences and heteropolysaccharidic glycopeptides. These different fractions were explored in vitro for their ability to interact with cell membranes. In fact, only fractions containing the heterogenous material agglutinated human transformed or embryonic cells within 2 h. The cell agglutination was specifically inhibited by N-acetylosamines and N-acetylneuraminic acid. An additional incubation of 20 h at 3 7 °C of the agglutinated cells, maintained in a minimal medium devoid of serum, led to a morphological change of the transformed cells due to an increased cell adhesion and cell spreading. These experimental data suggest that the basement membrane possesses active sites -consisting of an association between collagen and structural glycoproteins – which could play a primordial role in cell matrix interactions.
Hormone-Sensitive Adenylate Cyclase in Glomerular Cells
Authors: Paietta E. , Schwarzmeier J.D. , Simbruner G. , Latzka U. , Lubec G.
Published: November 2008

Using the adenylate cyclase assay after Ross we examined hormone sensitivity of isolated glomerular cells. cAMP production was increased 1.3–1.6-fold by stimulation with isoproterenol, 1.5–1.8 times by prostaglandin E1 and 1.4–1.5 times by histamine. The isoproterenol reaction could be completely inhibited by propranolol, the histamine effect was abolished by the H2-blocking agent cimetidine. As control we applied sodium fluoride, which directly activates the catalytic adenylate cyclase unit, increasing the activity 1.8–2.7 times (depending on the method of homogenization). These findings could reflect some physiological or pathophysiological implications, which are discussed in the present report.
Influence of Streptozitocin-Induced Diabetes on Glycosyltransferase Activities in Plasma and Renal Cortex
Authors: Heathcote Godfrey , Elliott Christine , Smith Eileen , Menashi Suzanne , Grant Michael E.
Published: November 2008

The collagen glucosyltransferase of renal cortex is increased in experimental diabetes and this increase may be partially reversed or prevented by insulin treatment. The absence of any consistent increase in the plasma collagen glucosyltransferase level in diabetes argues against the enzyme’s having a significant role in the pathological thickening of capillary basement membranes. The biological significance of the increased renal glucosyltransferase activity in chemically-induced diabetes must therefore remain in doubt but it is possible that the high glucose concentration in the blood simply stimulates the synthesis of new enzyme protein in the kidney.
Stimulatory Effect of Calcium Ions on p-Aminohippurate Accumulation by Rat Kidney Cortical Slices
Authors: Matsushima Yohkazu , Gemba Munekazu
Published: November 2008

The effect of external Ca2+ on p-aminohippurate (PAH) transport was examined using rat kidney cortical slices. External Ca2+ increased the initial rate of PAH uptake, markedly enhanced its maximal accumulation at steady-state conditions and depressed the efflux. Kinetic studies revealed that increasing external Ca2+ from 0 to 2.5 mM resulted in an increase in the Vmax of transport, while the apparent Km values remained constant. When the intracellular Na+ levels of the slices were equal, PAH accumulation was increased in the presence of Ca2+.A divalent cation such as Ba2+, Mn2+ or Sr2+ enhanced PAH accumulation to at least the same degree as Ca2+. While Mg2+ had no effect, La3+ exhibited a little stimulatory effect on the PAH accumulation. We suggest that the stimulatory action of Ca2+ on PAH accumulation is in part dissociated from that of Na+ gradient and that Ca2+ can be substituted by Ba2+, Mn2+ and Sr2+ with regard to the stimulation of PAH accumulation.
Effect of Bradykinin on Renal Function in Dogs Treated with Indomethacin or Propranolol
Authors: Yun John C.H. , Gill, Jr. John R. , Bartter Frederic C. , Kelly Gerald D. , Keiser Harry R.
Published: November 2008

The effect of bradykinin (BK) on renal function was examined in anesthetized dogs with or without treatment with either indomethacin or propranolol. Renal arterial infusion of BK (3 μg/min) in control dogs produced a sustained increase in urine flow rate (V), sodium excretion (UNaV), potassium excretion (UKV), and renal plasma flow (RPF) without a consistent change in glomerular filtration rate (GFR) or renin secretion rate (RSR). This increase in salt and water excretion and in RPF could not be blocked with indomethacin (5 mg/kg, followed by 2.1–3.2 mg/kg/h, i.v.). UNaV was 20.8 ± 7.4 and 123.3 ± 22.3 μEq/min (mean ± SEM values) before and after 140 min of infusion of BK (p < 0.005), respectively. Beta-receptor blockade with propranolol (5 mg/kg, followed by 2.8–3.4 mg/kg/h, i.v.) did not prevent the BK-induced rise in salt and water excretion, or in RPF. UNaV was 26.0 ± 9.7 and 96.4 ± 21.5 μEq/min before and after 140 min of infusion of BK (p < 0.005), respectively. The data suggest that the effects of BK on renal handling of salt and water and on RPF are not mediated by either prostaglandins or beta receptors.
Functional Compensatory Changes after Unilateral Nephrectomy in Rats
Authors: Lopez-Novoa J.M. , Ramos B. , Martin-Oar J.E. , Hernando L.
Published: November 2008

Cardiac output (CO), total peripheral resistance (TPR), renal blood flow (RBF), renal vascular resistance (RVR) and intrarenal blood flow distribution have been measured 48 h after unilateral (right) nephrectomy (UNX) and in sham-operated rats (SO). Glomerular filtration rate (GFR) and renal plasma flow (RPF) were determined using standard inulin and PAH clearances. Superficial single nephron GFR (SNGFR) was measured by free-flow micropuncture techniques. Extracellular fluid volume (ECV) and plasma volume (PV) were also determined. UNX rats showed increases of 17.4% in remnant kidney GFR and 34.5 % in RPF. Filtration fraction was decreased to 0.27 ± 0.01 (control value 0.31 ± 0.01; p < 0.0025). SNGFR was 45% higher in UNX rats and the ratio SNGFR/GFR increased by 28%. Cardiac output also increased (33.6 ± 1.0 for UNX rats; 28.0 ± 1.2 ml/min/100g BW for SO rats; p < 0.0025) accompanied by a corresponding fall (20%) in TPR. Left kidney RBF increased by 22%, whereas RVR decreased by 21%. Blood flow through individual glomer-uli increased in the outer and inner cortex and was unchanged in the midcortex. In conclusion, 48 h after unilateral nephrectomy, rats showed a hyperdynamic circulatory state with increased CO and decreased TPR; this could be involved in the acute adaptive functional and renal changes reported after uninephrectomy.
Prostaglandins Participate in the Regulation of NaCl Absorption in the Diluting Segments of the Nephron in vivo: Effects of Furosemide
Authors: Düsing Rainer , Nicolas Volkmar , Glänzer Kilian , Kipnowski Jochen , Kramer Herbert J.
Published: November 2008

Various studies point to a role of the renal prostaglandin (PG) system in the regulation of renal NaCl excretion. In the present experiments, distal delivery of proximal tubular fluid (DD) [(CH2O+Ccl)/GFR×100] and distal fractional chloride absorption (DFAC1) [CH2O/(CH2O+Cα)] were studied in 6 healthy volunteers undergoing sustained water diuresis. Studies of renal function were performed during intravenous infusion of hypotonic (0.45%) saline and during additional treatment with indomethacin, furosemide and furosemide plus indomethacin. Hypotonic saline was infused at increasing rates of 0.09, 0.18, and 0.36ml min-1 kg-1 body weight each for a 45-min period. DD over all three clearance periods averaged 8.27 + 0.71 ml min-1 100 ml-1 glomerular filtration rate (GFR) during saline infusion alone and was unchanged by indomethacin (8.09 ± 0.63 ml min-1100 ml-1 GFR).DFAC1 averaged 0.79 + 0.02 during saline and significantly increased to 0.87 + 0.01 (p < 0.002) during concomitant indomethacin treatment. Increased NaCl absorption in the diluting segment during indomethacin was paralleled by a decrease in urinary excretion of chloride (UC1V) from 221 + 29 during control to 124 ± 19 µEq/min (p < 0.025) and in urinary excretion of PGE2 (UPGE2V) from 1.45 + 0.12 to 0.51 + 0.09 pmol/min (p < 0.025). Furosemide increased UPGE2V to 2.94 + 0.34 pmol/min (p < 0.05) and UC1V to 2,590 + 128 µEq/min (p < 0.001). This effect was associated with an increase in DD to 26.70 + 1.33 ml min-1 100 ml”1 GFR (p < 0.001) and a decrease in DFACl to 0.19 ± 0.02 (p < 0.001). Neither DD and DFACl nor UClV were altered during furosemide+indomethacin as compared to furosemide in spite of a marked suppression of UPGE2V to 0.56 ± 0.13 pmol/min. Our results support the concept that renal PG participate in the regulation of NaCl absorption in the diluting segments of the nephron. Furthermore, the tubular effects of furosemide appear not to be mediated by the PG system.
Long Chain Fatty Acid Transport by the Perfused Rat Kidney
Authors: Trimble Mary Ellen
Published: November 2008

Transport of the long chain fatty acid (LCFA), palmitate (C16), was studied in the isolated rat kidney perfused with Krebs-Henseleit bicarbonate buffer containing 1% defatted albumin. Because palmitate was extensively bound to albumin, its filtration was negligible and transport into renal tubular cells occurred across the peritubular membrane. Saturation of peritubular uptake of palmitate was observed with a maximum uptake of 2.4–2.5 µ mol·g wet weight -1·20 min-1. Under the conditions of these experiments, uptake was not affected by attempts to alter fatty acid metabolism, by substances known to be transported by the organic acid transport system or by other LCFA.
Effects of Ischemia on Metabolite Concentrations in Dog Renal Cortex
Authors: Cunarro Julia A. , Schultz Stephanie E. , Johnson William A. , Weiner Michael W.
Published: November 2008

To investigate the effects of ischemia on renal metabolites, sequential slices of renal cortex were removed during 5 min of renal artery occlusion and for 5 min after release of occlusion. ATP concentrations rapidly fell during ischemia and rose during the post-ischemic period. Based on the rate of decline of ATP concentrations, the rate of ATP production was estimated to be 0.5 µ mol ATP/g/min. This is considerably less than the rate of ATP production estimated from renal O2 consumption. During ischemia, AMP concentrations rose, confirming the activity of adenylate kinase. The control lactate/pyruvate ratio suggested that dog kidney cytosol is more reduced than the cytosol of rat liver and kidney. During ischemia, the lactate concentrations and the lactate/pyruvate ratio of dog renal cortex increased as expected, and fell after restoration of blood flow. β-Hydroxybutyrate concentrations were considerably lower than those previously reported for rat liver and kidney. The β-hydroxybutyrate/acetoacetate ratio was not measurable during ischemia. However, the mitochondrial redox state, calculated from the glutamate/α-ketoglutarate·NH+4 ratio, was similar to previous reports and this ratio appropriately changed during the ischemic and post-ischemic period.
Validity of 15-μm Microspheres in Studying Intrarenal Blood Flow Distribution in the Newborn Dog
Authors: Kotagal Uma R. , Kleinman Leonard I.
Published: November 2008

In order to determine the effect of axial streaming on the distribution of 15-µm microspheres, and hence its validity in studying intrarenal blood flow distribution, renal blood flow and intrarenal blood flow distribution were measured in 4 newborn dogs using 9-and 15-µm microspheres. In 4 other newborn dogs, similar studies were done under polycythemic conditions (hematocrit > 65%) when the flow conditions might be altered. There were no differences in renal blood flow or intrarenal blood flow distribution using 9- and 15-µm microspheres. Thus from the present study, it appears that 15-µm microspheres reflect true intrarenal blood flow distribution in the newborn dog.
Contralateral Renal Function Following Unilateral Renal Artery Constriction
Authors: Murray Robert D. , Hackenthal Eberhard , Mittmann Ulrich , Gross Franz
Published: November 2008

The acute (0.5–3.0 h) response of the contralateral kidney to unilateral renal artery constriction was studied in 7 pentobarbital-anesthetized dogs. Within 30 min after unilateral renal artery constriction to a pressure of about 60 mm Hg, contralateral vascular resistance, sodium excretion and filtration fraction increased significantly while glomerular filtration rate, blood flow and plasma flow did not change. Renin secretion decreased dramatically within 30 min, demonstrating a negative venous minus arterial plasma renin activity in some dogs. Unilateral renal artery constriction did not change the rate of angiotensin II extraction across the contralateral kidney or the urinary renin activity (measured in 4 dogs). These results indicate that the acute response of the contralateral kidney to unilateral renal artery constriction is somewhat different from that seen in the chronic state.
Development of Renal Function in the Rat
Authors: Provoost Abraham P. , de Keijzer Marinus H. , Wolff Erik D. , Molenaar Jan C.
Published: November 2008

Clearance methods, allowing for repeated use in the same animals, were applied in a cross-sectional study to establish the normal increase in renal function in rats. It was shown that the glomerular filtration rate (GFR) and the effective renal plasma flow (ERPF) per gram of kidney was low in the 4-week-old rats. Levels comparable to those of adult rats were reached at an age of about 7 weeks. From that age on the GFR and the ERPF, as well as kidney weight, increased at a lower rate than did the body weight. The present findings, obtained by these rather simple techniques are, in general, concurrent with data from the literature on the development and maturation of renal function in rats.
Influence of Alterations in Acid-Base Conditions on Intracellular pH of Intact Renal Cortex
Authors: Jones Bernard , Simpson David P.
Published: November 2008

Intracellular pH (pHI) of intact rat renal cortex was estimated using [14C]-5,5-dimethyl-2,4-oxazolidinedione and 22Na+ under conditions of metabolic acidosis and alkalosis, potassium depletion and carbonic anhydrase inhibition. In metabolic acidosis and alkolosis, pHI and bicarbonate concentration changed in the same direction as occurred in plasma. In potassium depletion, systemic acid-base balance was unaltered but a marked intracellular acidosis developed. Carbonic anhydrase inhibition with acetazolamide was associated with an extracellular respiratory acidosis and a rise in intracellular bicarbonate concentration. Another carbonic anhydrase inhibitor, benzolamide, caused no change in systemic acid-base state but produced a decrease in intracellular bicarbonate concentration. When appropriate corrections were made for predicted change in tubular fluid bicarbonate and for intracellular sodium, modification in the absolute values of the above changes occurred but the directions of the changes in pHI and bicarbonate concentration were unaltered.
Distribution of Glomeruli in the Renal Cortex of Munich Wistar Frömter (MWF) Rats
Authors: Hackbarth H. , Büttner D. , Jarck D. , Pothmann M. , Messow C. , Gärtner K.
Published: November 2008

The glomerular distribution in the renal cortex of the Munich Wistar Frömter (MWF) rat, a substrain of the Munich Wistar rat selected for superficial glomeruli, was compared to that of a control strain (LEW/Ztm) between 10 and 150 days of age. While there were no significant differences in body growth, kidney weight, or growth of the renal cortex in these two strains, the average diameter of Bowman’s capsule and of the glomerular tuft was significantly larger (about 12%) in rats of the MWF strain which were older than 60 days. In histological sections of kidneys of MWF rats in all age groups, many glomeruli in direct contact with the renal capsule were found; thus, this developmental step must have taken place before 10 days of age. The appearance of superficial glomeruli was due to a shift of glomeruli to a position just under the renal surface, the subcapsular zone or ‘cortex corticis’, which is normally free of glomeruli. For the rest of the renal cortex there were only slight differences in glomerular density and in total number of glomeruli per section between these two strains. These results lead us to suppose that superficial glomeruli belong to a special nephron type; thus, these glomeruli are not enveloped by parts of the proximal tubule.
Changes in Glomerular and Cortical Tubular cAMP Metabolism in Kidneys from Rats with Unilateral Ureteral Obstruction
Authors: Schlondorff Detlef , Satriano Joseph A. , Trizna Walter , Weber Herbert
Published: November 2008

Obstructive uropathy is associated with changes in several renal functions. As some of these are mediated by cAMP, we examined whether changes in cAMP metabolism could contribute to the pathophysiology of unilateral ureteral ligation in rats. We found that basal adenylate cyclase in the cortex of the obstructed kidney doubled after 3-7 days, but the response to NaF and parathyroid hormone was decreased. Similarly, in vivo infusion of parathyroid hormone resulted in lower cAMP levels in the cortex of the obstructed kidney. Parathyroidectomy or pretreatment with beta-adrenergic blocker had no effect. Prostaglandin inhibition by indomethacin decreased, but did not abolish, the differences.On the other hand, basal adenylate cyclase in glomeruli from contralateral kidneys was higher. Pretreatment with indomethacin reduced the basal activity in contralateral glomeruli, and led to increased degrees of stimulation with parathyroid hormone and prostaglandins.Furthermore, we demonstrated that isolated glomeruli contain cAMP-dependent protein kinase that is found predominantly in the 30,000 g supernatant fraction and that by DEAE-cellulose chromatography has the characteristics of a type II kinase. In glomeruli from rats with unilateral ureteral ligation, the distribution and degree of activation of the cAMP-dependent protein kinase are affected differently on the ligated and contralateral sides, probably reflecting the change in glomerular cAMP generation.These results indicate that changes in cAMP metabolism may contribute to the altered cortical tubular function in unilateral ureteral ligation and may be partially related to enhanced prostaglandin synthesis in the obstructed kidney. On the other hand, the higher adenylate cyclase activity and the change in cAMP-dependent protein kinase activity in glomeruli from the contralateral kidney may in part reflect increased PGE2 production by these glomeruli. The results support the concept that similar to their in vitro action, locally generated prostaglandins may in vivo affect cortical tubular function by influencing the tubular cAMP system while those generated in the glomerulus alter glomerular cAMP metabolism.
Intermolecular Reducible Cross-Links in Rat Glomerular Basement Membrane
Authors: Wu Van-Yu , Cohen Margo Panush
Published: November 2008

Glomerular basement membrane (GBM) was purified from adult rats and treated with tritiated borohyride for analysis of the reducible cross-links. After acid hydrolysis, samples were subjected, with and without prior gel filtration on Biogel P-2, to a chromatographic system standardized with known cross-links. The major peak of radioactivity co-eluted with authentic di-hydroxylysinonorleucine (di-OHLNL) standard. Derivation of this cross-link from lysine was corroborated by demonstrating its presence in GBM purified after incubation of isolated glomeruli with [14C]-lysine and after in vivo injection of [14C]-lysine. GBM labeled in vitro with radioactive lysine also contained peaks co-eluting with hydroxylysinonorleucine and lysinonorleucine standards, as well as at unidentified positions in the chromatogram. The findings indicate that rat GBM contains lysine-derived cross-links, of which di-OHLNL is the major reduced form.
Effect of Changes in Perfusion Pressure on Renal and Urinary Kallikrein in the Isolated Perfused Rat Kidney
Authors: Bönner G. , Schwertschlag U. , Marin-Grez M. , Gross Franz
Published: November 2008

Kallikrein activity in urine and in the renal cortex of the isolated rat kidney, perfused at constant pressure, decreased, while renal perfusate flow, glomerular filtration rate, excretion of sodium and of potassium and urine flow remained unchanged. Abrupt changes in perfusion pressure resulted in corresponding changes in renal perfusate flow, glomerular filtration rate, excretion of sodium and of potassium and urine flow. Urinary kallikrein increased little and transiently only, each time perfusion pressure was elevated. At the end of the experiments, a marked decrease in kallikrein activity in the renal tissue was found. From these results, it might be concluded that the excretion of kallikrein from the isolated perfused rat kidney resulted in a marked depletion of kallikrein stores in the kidney, probably due to an insufficient kallikrein synthesis.
Effect of Ischemia and Hypertonic Saline Loading on Renal Adenine Nucleotides
Authors: Urbaitis Barbara Knutsen
Published: November 2008

The present study was done to determine: (1) regional (cortex, red medulla and papilla) changes in ATP, ADP and AMP resulting from periods of ischemia of 30-300 s; (2) whether ischemic changes in adenine nucleotides or lactate were modified by hypertonic saline loading, and (3) whether adenylate kinase activity was present in each region. Ischemia led to changes in all three adenine nucleotides which were characteristic for each region. In cortex, there was a major decrease in ATP, increase in AMP and a small transient increase in ADP. In red medulla there were slower changes in ATP, ADP and AMP. In papilla, ATP decreased slightly and ADP, as opposed to AMP, accumulated. Hypertonic saline loading increased the rate of ATP decrease and AMP accumulation, most markedly in red medulla. Lactate concentration rose similarly in control and hypertonic saline studies. Adenylate kinase activity was found to be present in each region. In conclusion: (1) the rate of change of all three adenine nucleotides differs among the three renal areas studied; (2) increases in renal transport work, associated with hypertonic saline loading, are reflected in an increase in the rate of ATP decay during ischemia; (3) anaerobic metabolism, as indicated by tissue lactate concentration, is not altered by hypertonic saline loading, and (4) the failure of AMP to accumulate in papilla is not due to the absence of adenylate kinase.
Compositional Changes of the Corticopapillary Osmotic Gradient during Dehydration in the Absence of Vasopressin
Authors: Williamson Gail L. , Edwards Brian R.
Published: November 2008

Despite the absence of vasopressin, Brattleboro homozygous (DI) rats concentrate their urine to hypertonic levels when deprived of drinking water. Ultimately this rise in urine osmolality must follow from increased osmolality of the corticopapillary gradient and/or increased osmotic equilibration across the collecting ducts. In this study we examined the concentrations and contents of total solute, urea, and nonurea solute in tissue from cortex to papillary tip of DI rats before and after dehydration for 12, 24, and 48 h. The greatest increase in osmolality occurred during the first 12 h; both urea and nonurea solute concentrations increased, but urea preferentially. From 12 to 48 h there were only small further increases in these concentrations, largely as a result of decreased tissue water content. Osmotic equilibration (reflected by urine/papillary tip osmolality) increased dramatically during dehydration, presumably because of decreased flow rate, attaining full equilibration by 48 h. The rise in urine osmolality during the first 12 h of dehydration was due to increased osmotic equilibration and to the enhanced corticopapillary gradient; urine became more concentrated from 12 to 48 h largely as a result of increased osmotic equilibration.
The Renal Brush Border Membrane in Man
Authors: Béliveau Richard , Brunette Michèle G.
Published: November 2008

Brush border membranes (BBM) have been prepared from fresh samples of normal human kidney cortex and compared to that from mouse, rat, and rabbit. Human BBM presents a sodium dodecyl sulfate gel electrophoresis protein pattern similar to that of the animal species with 22 proteins having the same molecular weight (MW). Incubation with inorganic 32P reveals a phosphate-binding protein (MW 78,000) common to the animal species. However, the binding capacity is lower in man: 4.3 ± 2.2 pmol Pi/mg protein compared to 9.9 ± 2.1, 29.7 ± 4.3, and 31.1 + 5.2 in rabbit, mouse, and rat, respectively. The MW of the binding protein corresponds to that of the monomer of alkaline phosphatase. Alkaline phosphatase activity follows the same increasing order in the four species. The Na gradient-dependent Pi uptake by human BBM vesicles is low: Vmax is 0.90 + 0.05 nmol/mg/ 20 s compared to 1.3 + 0.1, 1.5 + 0.2, and 5.2 + 0.2 in rabbit, mouse, and rat, respectively. However, the Km values are within the same range for the four species.
Suppression of Proteinuria by Dipyridamole in Rats with Aminonucleoside Nephropathy
Authors: Nagase Mitsumasa , Kumagai Hiromichi , Honda Nishio
Published: November 2008

Nephrosis was induced by single injections of puromycin of aminonucleoside to rats which were divided into two groups; the experimental group receiving dipyridamole in addition to aminonucleoside and the control group receiving aminonucleoside alone. 24-hour urinary albumin increased in rats of both groups after aminonucleoside injections. However, the experimental rats excreted significantly less albumin than controls. On the contrary, there was no significant difference in urinary IgG between the two groups. The stainings of anionic sites of glomerular basement membrane using ruthenium red revealed the reduction of anionic charge in the glomerular basement membrane of both groups, but the decrease of anionic charge was suppressed in lamina rara interna of the experimental rats. Considering the role of charge barrier in the glomerular basement membrane, it is concluded that the maintenance of anionic charge in experimental rats is causally related to the suppressed excretion of albumin.
Changes in Salt Intake Alter the Release of Multiple Renin Species in a Nonuniform Manner
Authors: Katz Stephen A. , Malvin Richard L.
Published: November 2008

Six distinct forms of renin were found to be released from rat renal cortical slices incubated in vitro. The multiple renin forms were demonstrated using shallow gradient isoelectric focusing, and focused at pH 5.7, 5.55, 5.3, 5.15, 4.9 and 4.8. Before renal cortical slices were prepared, rats were given free access to both high- and low-salt diets containing, respectively, 0.2 or 0.005 mEq Na+/g food. Renal cortical slices prepared from rats maintained on the high-salt diet for 8 days (group I) released significantly different proportions of the six renin forms as well as less total renin when compared to rats first maintained on the high-salt diet for 8 days followed by the low-salt diet for 8 additional days (group II). In a second series of experiments, renal cortical slices prepared from rats maintained on the low-salt diet for 19 days (group III) secreted significantly different proportions of the six renin forms, as well as more total renin when compared to rats first maintained on the low-salt diet for 10 days, followed by the high-salt diet for 4 additional days (group IV). These studies demonstrate that the relative proportions of released multiple renin forms change when the kidney alters its renin secretory rate in response to changes in Na+ intake.
Renal Albumin Reabsorption in Normal and Sodium Maleate-Treated Rats
Authors: Cho Joan , Galaske Rainer G. , Arbesman Harvey , Van Liew Judith B.
Published: November 2008

The normal filtered load of albumin at the rat glomerulus was estimated to be 18 mg/24 h × g kidney weight by means of micropuncture studies. Total nephron fractional reabsorption was 91%. The proximal convoluted tubule accounted for 72% of total reabsorption followed by an additional 12% in the loop of Henle. Only minimal protein uptake occurred in more distal parts of the nephron. Na maleate, given at a dosage of 2 mM/kg body weight 2 h prior to micropuncture, inhibited tubular albumin uptake in the proximal convoluted tubule. As in controls there was no measurable protein uptake beyond the loop of Henle. These results indicated that tubular reabsorption of albumin was virtually completed by the early distal convoluted tubule. Maleate was found to be a potent inhibitor of protein transport in the proximal convoluted tubule resulting in a fractional excretion of albumin of 50%.
Interrelation between Oxygen Consumption and Na-K-ATPase Activity in Rat Renal Proximal Tubule Suspension
Authors: Gstraunthaler Gerhard , Pfaller Walter , Kotanko Peter
Published: November 2008

The portion of Na-K-ATPase activity on oxygen consumption was determined in suspensions of rat proximal tubules by monitoring oxygen consumption (QO2) under different metabolic states: in the presence or absence of succinate or lactate (10 mmol/l) and increasing concentrations of ouabain (0.4; 0.8; 1.2 and 1.6 mmol/l). In the metabolic states tested, the ouabain induced decrease of QO2 was identical, which implies a fixed rate between Na-K-ATPase activity and QO2. On the basis of these results, Ki and maximal inhibition rate were determined by Lineweaver-Burk and Eadie-Hofstee plots. Ki was 0.67 mmol/l ouabain and the maximal inhibition of QO2 was 77%. This corresponds to an absolute decrease of QO2 of 1,630 µmol O2 h-1 g-1 protein. Since this value represents the real portion of Na-K-ATPase on QO2, the activity of Na-K-ATPase can be calculated, yielding an activity of 163 µmol ATP min-1 g-1 tubule protein.
Inhibition of Protein Reabsorption in the Renal Proximal Tubule by Basic Amino Acids
Authors: Ottosen Peter D. , Madsen Kirsten M. , Bode Folkert , Baumann Karl , Maunsbach Arvid B.
Published: November 2008

The effects of basic and neutral amino acids on the reabsorption of 125I-lysozyme by the renal proximal tubule were examined in rats. In whole animal experiments control animals were given an intravenous (i.v.) injection of 125I-lysozyme alone while experimental animals received an i.v. injection of either a basic or a neutral amino acid prior to the injection of 125I-lysozyme. In control animals the renal content of 125I-lysozyme 30 min after injection was 35% of the injected dose. After injection of basic amino acids there was a significant decrease in the renal uptake of lysozyme. There was no effect of neutral amino acids on the reabsorption of lysozyme. In microperfusion experiments proximal convoluted tubules were perfused in vivo for 3 min with a solution containing 125I-lysozyme and either lysine or alanine. In tubules perfused with lysine there was a significant decrease in the reabsorption of lysozyme, whereas alanine had no effect on lysozyme uptake. Electron microscope autoradiography revealed that lysozyme was located in endocytic vesicles and lysosomes in both experimental groups. However, the autoradiographic grain density was significantly decreased in tubules perfused with lysine as compared with those perfused with alanine. These findings demonstrate that basic amino acids inhibit the reabsorption of the cationic protein lysozyme by the proximal tubule cells.
Renal Adaptation to Additional Nephrons: A Functional Study in the Three-Kidney Rat
Authors: Provoost Abraham P. , van Aken Matthijs
Published: November 2008

Renal functional adaptation to additional nephrons was studied in rats in which a third kidney was transplanted isogeneically. Total renal function did not increase when an extra kidney was added. Quantitation of the contribution of each kidney, by means of a 99mTc-DTPA scan, showed that the glomerular filtration rate of the native kidneys had decreased to counterbalance the added function. The glomerular filtration rate of the transplanted kidney as well as its number of glomeruli were 20% less than that of the intact native kidneys. The present findings once again illustrate the kidney’s remarkable capacity for functional adaptation to a change in the total number of nephrons.
Enhancement of Renal Prostaglandin E2 and Renin Release by Autoregulatory Dilation of Preglomerular Vessels in Dogs
Authors: Vikse Arild , Kiil Fredrik
Published: November 2008

To examine the PGE2 and renin release during autoregulatory dilation of preglomerular vessels, experiments were performed in three groups of anesthetized dogs. [1] By reducing the arterial perfusion pressure from 113 + 3 to 78 ± 3 mm Hg, renin release rose to 20 + 5% and PGE2 release to 74 + 12% of the maximal values attained at two perfusion pressures below the range of autoregulation. [2] During ureteral occlusion, PGE2 and renin release rose to maximal values already at control blood pressure and remained unaltered as the arterial perfusion pressure was reduced from 124 + 7 to 68 + 2 mm Hg. Renal blood flow fell in proportion to the perfusion pressure indicating abolished autoregulation. [3] At a perfusion pressure below the range of autoregulation, saline infusion restored sodium excretion and reduced renin release but did not alter PGE2 release. We conclude that PGE2 release is raised by autoregulatory dilation of preglomerular arteries. Prostaglandins enhance renin release when afferent arterioles are dilated. Renin release mediated by a macula densa mechanism is not PGE2 dependent.
On the Mechanism of Renal Vasoconstriction Induced by Acetylcholine in Indomethacin-Treated Dogs
Authors: Ho Sai-Sun , Yun John C.H. , Gill, Jr. John R. , Kelly Gerald D. , Keiser Harry R.
Published: November 2008

Renal arterial infusion of acetylcholine (ACh) in control dogs produced a natriuresis and diuresis and an increase in renal plasma flow (RPF) without a change in glomerular filtration rate (GFR) or in renin secretory rate (RSR). In dogs pretreated with indomethacin (Indo), an inhibitor of prostaglandin synthetase, renal arterial infusion of ACh first produced a rise, then a decline in urine flow, sodium excretion (UNaV) and GFR that was accompanied by a progressive fall in RPF and a progressive rise in RSR. The rise in RSR was potentiated by renal arterial infusion of an alpha-adrenergic receptor blocker, phenoxybenzamine (Phenoxy), and attenuated, but not completely abolished, by beta-adrenergic receptor blockade with propranolol (Prop). Chemical denervation with reserpine alone, or in combination with chronic surgical renal denervation, failed to prevent the fall in RPF, GFR and UNaV and the rise in RSR produced by ACh in Indo-treated dogs. Renal arterial infusion of Phenoxy and intravenous infusion of Prop, alone or in combination with renal arterial infusion of an angiotensin II antagonist, saralasin, failed to maintain the vasodilatory, diuretic and natriuretic effects of ACh in Indo-treated dogs. Elimination of endogenous vasopressin by hypophysectomy also failed to prevent the vasoconstriction induced by ACh in Indo-treated dogs. The results suggest that ACh produced renal vasoconstriction in Indo-treated dogs by mechanism(s) other than an increase in renal adrenergetic activity or an increase in the activity of the renin-angiotensin system. The results also suggest that the vasoconstriction was independent of vasopresin.
Properties of an Ecto-5’-Nucleotidase of the Renal Brush Border
Authors: Le Hir Michel , Angielski Stefan , Dubach Ulrich C.
Published: November 2008

A decrease of glomerular filtration rate can be observed during accelerated catabolism of ATP in kidney. It has been proposed that this effect is due to the increase in the renal production of adenosine from ATP. The last reaction in the pathway concerned is the conversion of 5’-AMP to adenosine. We found that brush border membranes purified from homogenates of the rat renal cortex carry out this reaction. The enzyme involved in the hydrolysis has the characteristic properties of ecto-5’-nucleotidases: It is inhibited by ATP, ADP, and by α, β-methyleneadenosine-5’-diphosphate, and it is not stimulated by magnesium. All catalytic sites are accessible from the outside of the vesicles. The Km of the enzyme for 5’-AMP is 5.77 µM. The enrichment of the 5’-AMP-hydrolyzing activity in the brush border fraction as compared to the homogenate is 9.2 ± 1.5 times. Histochemical staining of kidney sections reveals hydrolysis of 5’-AMP only at the brush border of the proximal tubule. We conclude that the brush border of the proximal tubule of the rat kidney possesses an ecto-5’-nucleotidase which has the same properties as the ecto-5’-nucleotidases in other tissues.
Acute Effects of Various Diuretics on Lithium Clearance
Authors: Thomsen Klaus , Leyssac Paul P.
Published: November 2008

Previous studies have shown that the clearance of lithium (Cli) is a quantitative measure of the delivery of tubular fluid to Henle’s loop in rats given food with an ordinary or high sodium content, but not in rats given food with a low sodium content, because under these latter circumstances lithium is also reabsorbed to some extent in the distal nephron. The present study examines the effect of acetazolamide, hydrochlorothiazide, furosemide, and amiloride on the distal reabsorption of lithium in conscious rats with hereditary diabetes insipidus fed standard diets with medium (300 mmol Na/kg) and low (5 mmol Na/kg) sodium contents, respectively. Low sodium diet induced distal Li reabsorption, as apparent from the decrease in CLi and a fall in the urine/plasma lithium concentration ratio (U/P)Li to below 1.0. Amiloride and furosemide abolished the distal Li reabsorption. Acetazolamide also abolished distal Li reabsorption and, in addition, it increased the fluid output from the proximal tubules. Hydrochlorothiazide was unable to abolish distal Li reabsorption.