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PubMed1967

The intracellular ratio of cysteine and cystine in various tissues.

1. The cysteine-cystine ratio was measured in rat kidney cortex, diaphragm, jejunum, liver and brain. 2. This ratio was determined by incubating these tissues in buffer containing [(35)S]cystine and then homogenizing the tissue in a buffered solution of N-ethylmaleimide. The products of this reaction were separated by high-voltage electrophoresis and the radioactivity in the cystine and 2-(l-2'-amino-2'-carboxyethylthio)-N-ethylsuccinimide regions was determined. 3. In these tissues cyst(e)ine was mainly present in the reduced form. 4. After incubation of [(35)S]cystine with rat jejunal segments it was found that 36% of the cystine in the medium has been reduced. 5. Anaerobiosis, Na(+)-free media, glucose and high concentrations of cystine and lysine were found not to affect significantly the cysteine-cystine ratio in rat kidney-cortex slices.

Animals↗
PubMed1997

Localization of the high-affinity glutamate transporter EAAC1 in rat kidney.

Most amino acids filtered by the glomerulus are reabsorbed in the kidney via specialized transport systems. Recently, the cDNA encoding a high-affinity glutamate transporter, EAAC1, has been isolated and shown to be expressed at high levels in the kidney. To determine the potential role of EAAC1 in renal acidic amino acid reabsorption, the distribution of EAAC1 mRNA and protein in rat kidney was examined. In situ hybridization revealed that EAAC1 mRNA is expressed predominantly in S2 and S3 segments of the proximal tubules and at low levels in the inner stripe of outer medulla and inner medulla. Polyclonal antibodies raised against the carboxy terminus of EAAC1 recognized a single band of approximately 70 kDa on Western blots of membrane protein from kidney cortex and medulla. Immunofluorescence microscopy revealed intense signals in the luminal membrane of S2 and S3 segments and weaker signals in S1 segments, descending thin limbs of long-loop nephrons, medullary thick ascending limbs, and distal convoluted tubules. These results are consistent with EAAC1 encoding the previously described apical high-affinity glutamate transporter in the kidney that mediates reabsorption of acidic amino acids in tubules beyond early proximal tubule S1 segments. Potential additional roles of EAAC1 in acid/base balance, cell volume regulation, and amino acid metabolism are discussed.

Amino Acid Transport System X-AG↗
PubMed1972

Effect of prostaglandin E 1 on certain renal actions of parathyroid hormone.

Parathyroid hormone increased basal adenyl cyclase activity and that increase was inhibited by prostaglandin E(1) (PGE(1)). Tissue cyclic 3',5'-adenosine monophosphate (cyclic AMP) concentrations were increased by parathyroid hormone and that increase was likewise inhibited by PGE(1). Both parathyroid hormone and dibutyryl cyclic AMP increased (32)P incorporation into renal cortical phospholipids. PGE(1) diminished the effect of parathyroid hormone but not dibutyryl cyclic AMP to influence that parameter. PGE(1) likewise modulated the effect of parathyroid hormone but not dibutyryl cyclic AMP to decrease fractional phosphate reabsorption by the renal tubule. It is suggested that PGE(1) inhibits the effect of parathyroid hormone by decreasing its effect on adenyl cyclase. Such interaction may be important in modulating the intracellular action of parathyroid hormone on kidney cortex.

Adenylyl Cyclases↗
PubMed1991

Peroxisomal localization of the immunoreactive beta-oxidation enzymes in a neonate with a beta-oxidation defect. Pathological observations in liver, adrenal cortex and kidney.

A boy born to healthy, unrelated parents, presented at birth with hypotonia and seizures. Very long chain fatty acids in the plasma were strongly elevated; bile acid intermediates and plasmalogen biosynthesis were normal. Acyl-CoA oxidase activity was normal. The patient died at the age of 3 months. The cerebellum and medulla oblongata showed neuronal migration defects. The specific biochemical basis for the impaired peroxisomal beta-oxidation has not been found. The three immunoreactive peroxisomal beta-oxidation enzymes and catalase were localized in the hepatocellular peroxisomes. Aberrant features of the peroxisomes included: a subpopulation of organelles larger than 1 micron, an amorphous nucleoid in many organelles, and invaginations of the peroxisomal membrane into the matrix. Peroxisomes in the proximal renal tubules also contained the three immunoreactive beta-oxidation enzymes. Regularly spaced trilamellar inclusions were seen in hepatic macrophages; they were much more abundant in adrenocortical macrophages. The inclusions were birefringent and resistant to acetone extraction. Distinct hepatic fibrosis had developed over a period of 2.5 months. We speculate that the impaired beta-oxidation is due to a defect at the level of the peroxisomal carnitine octanoyl or -acetyl transferase, responsible for the export of beta-oxidation products.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1994

Renal D1 receptors, and not D2, are upregulated after aortic constriction and may be involved in cardiac hypertrophy.

1. The characteristics of dopamine (D) receptors were studied in kidney using the radiolabelled receptor assay of [3H]-SCH-23390 for D1 and [3H]-sulpiride for D2 receptors during cardiac hypertrophy. Male Sprague-Dawley rats (175-200 g) underwent abdominal aortic constriction above the renal arteries and were studied 28 days thereafter. Sham operated animals without aortic constriction were used as control. 2. Membranes obtained from kidney cortex showed an increase in the number of binding sites (Bmax) of D1 receptors in the aortic banded group. The apparent affinity for the ligand (Kd) was unchanged with D1 receptors, as compared to sham control. Both Bmax and Kd were unchanged for D2 receptors in the aortic banded group. 3. Autoradiographic data further reinforced the findings, showing an increased number of D1 receptors in the kidney at 28 days after abdominal aortic constriction. These changes were associated with an increase in plasma renin activity in the aortic banded group. Further, Na(+)-K(+)-ATPase as measured by fmol of 32Pi released from [gamma-32P]-ATP, was decreased in the kidney cortex of banded animals. 4. Reversal of hypertrophic parameters was observed in the aortic banded group treated for 14 days with SCH 23390 hydrochloride (0.1 mg kg-1 i.p.), a known D1 receptor antagonist. 5. The present study shows an upregulation of renal D1 receptors following abdominal aortic constriction and it is suggested that upregulation of D receptors may be involved in the development of cardiac hypertrophy.

Animals↗
PubMed1975

Identification and turnover of glycosaminoglycans in rat kidneys.

The turnover of sulfate label in crude glycosaminoglycan fractions from rat kidney cortex, medulla, and papilla has been determined. Heparan sulfate, chondroitin sulfate, dermatan sulfate, and hyaluronate have been separated electrophoretically and their specific activities determined after injection of labeled sulfate or glucose. The half-lives of the sulfated glycosaminoglycans are within the ranges found for other organs and tissues, but hyaluornate has a somewhat faster turnover in the kidney than elsewhere.

Animals↗
PubMed1998

Ibuprofen-induced changes in sulfate renal transport.

Nonsteroidal anti-inflammatory drugs (NSAIDs) increase sulfate renal clearance and decrease the fractional reabsorption of sulfate by the kidneys. The mechanism of this alteration of inorganic sulfate homeostasis is unknown. The objectives of this study were 1) to investigate if sulfate renal transport is altered in isolated membrane vesicles after pretreatment of animals in vivo with ibuprofen (IBU), and 2) to determine the cellular mechanism of changes in sulfate renal transport. Female Lewis rats received IBU at a i.v. dose of 27 mg/kg followed by an infusion of 33 microg/min for 4 hr. Sulfate transport was studied using brush border (BBM) and basolateral membrane (BLM) vesicles isolated from rat kidney cortex. The Vmax for the sodium-dependent sulfate cotransport (NaSi-1) in BBM was significantly lower in the IBU group compared with the control group (0.79 +/- 0.23 vs. 1.25 +/- 0.17 nmol/mg protein/10 sec, respectively; P <.05) with no change in Km. There were no significant differences between the study groups in sulfate anion exchange kinetics in BLM vesicles. NaSi-1 transporter mRNA level in kidney cortex and protein level in BBM were significantly lower in animals pretreated with IBU compared with that in control animals. There was no change in membrane fluidity of BBM and BLM isolated from IBU-treated animals as measured by the fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene. These results indicate that IBU treatment alters sodium-dependent sulfate cotransport by a downregulation of mRNA and protein of NaSi-1 transporter in BBM.

Animals↗
PubMed1981

The production of monoclonal antibodies against glomerular and other antigens of the human nephron.

During our studies on human kidney tubular antigens we have applied the technique of cell fusion for the preparation of monoclonal antibodies. For this purpose, plasma membranes were prepared from human kidney cortex by homogenization, fractionated on density gradients and selected according to brush border marker enzyme activity. Spleen cells from Balb/c mice hyperimmunized with plasma membranes were fused (PEG) with NS1 plasmocytoma cells by standard procedure. Culture supernatants were tested for presence of specific antibodies by indirect immunofluorescence with fluorescein-conjugated rabbit anti-mouse Fab antibodies on human kidney slices. In two fusions (210 wells), 70 positive hybrids were found secreting antibodies for a variety of antigens in the kidney. Most of them were directed against tubular antigens. In addition, as a by-product, we detected hybridomas which secreted antibodies specific for antigens in other parts of the nephron, such as glomeruli, blood cloning, and monoclonal antibodies were produced in large amounts from ascitic fluid. Some of these antibodies are specific for antigens of the basement membrane, others for antigens of the mesangium. Some recognize antigens present on glomeruli alone, others recognize antigens present on glomeruli and tubules or on glomeruli and blood vessels. We are convinced that the new immunological technique will yield better information on the antigenic microstructure of the nephron. In addition, the monoclonal and, by definition, monospecific antibodies might be useful for diagnostic purposes: recognition and quantitation of the corresponding antigens in the serum and/or urine of patients suffering from kidney diseases.

Antibodies, Monoclonal↗
PubMed1990

Candida albicans--do mycelia matter?

Growth of Candida albicans in the mycelial phase is neither necessary for initiation of infection in the kidney of the mouse, following intravenous inoculation, nor for the establishment of chronic renal colonization. However, mycelial formation would appear to be important in the establishment of pelvic lesions with their associated pathological changes. Two mycelia-less mutants, CA-2 and MM2002, in the early stages of infection tended to develop in the glomeruli of the mouse kidney cortex while the wild-type parent strains spread throughout the cortex and medulla, with only occasional involvement of glomeruli. The mutants appeared to stimulate a milder inflammatory response than the parent strains. In chronic infections with wild-type strains, tangled masses of mycelia filled the renal pelvis, but pyelonephritis and hydronephrosis did not depend on a persistent cortical infestation. Yeasts of the mutant strains persisted in the body of the kidney and stimulated a continuing neutrophil response. Systemic infections with wild-type strains were eliminated by treatment with low doses of an azole antifungal drug, ICI 195,739, or with amphotericin B, whereas systemic infections with the mutant strains were much reduced, but not eliminated, by relatively high doses of either of the two drugs. Unlike azole drugs, amphotericin B does not show differential activity against the two morphological forms of C. albicans. Because kidney infections with the mutant strains are relatively resistant to amphotericin B as well as the azole tested, we conclude that the impressive activity of azoles in vivo may not be explained entirely by their inhibition of mycelial growth.

Amphotericin B↗
PubMed1994

Cellular mechanisms of acute and chronic adaptation of rat renal P(i) transporter to alterations in dietary P(i).

Recently, the cDNA for a Na-P(i) cotransport system of rat kidney cortex (NaPi-2) has been identified by expression cloning. Using polyclonal antibodies raised against this renal Na-P(i) cotransport system, and using the polymerase chain reaction after reverse transcription of mRNA in microdissected nephron segments, we recently demonstrated that NaPi-2-related mRNA and protein is expressed in the brush-border membranes (BBM) of the proximal tubules of rat kidney. The purpose of the present study was to study the cellular mechanisms involved in adaptation of rat renal Na-P(i) cotransporter to acute and chronic alterations in dietary P(i). Compared with rats fed chronically (7 days) a high-P(i) diet (1.2%), in rats fed chronically a low-P(i) (0.1%) diet the 3.4-fold increase in BBM Na-P(i) cotransport rate (chronic upregulation) was associated with a 2.2-fold increase in renal cortical NaPi-2 mRNA and a 4.9-fold increase in BBM NaPi-2 protein abundances. In contrast, compared with rats fed chronically (7 day) a high-P(i) diet, in rats fed acutely (2 h) a low-P(i) diet the 1.5-fold increase in Na-P(i) cotransport rate (acute upregulation) was associated with a 1.8-fold increase in NaPi-2 protein but no change in NaPi-2 mRNA abundance. Similarly, compared with rats fed chronically a low-P(i) diet, in rats fed acutely (2 h) a high-P(i) diet the 1.9-fold decrease in Na-P(i) cotransport rate (acute downregulation) was associated with a 3.8-fold decrease in NaPi-2 protein but no change in NaPi-2 mRNA abundance.(ABSTRACT TRUNCATED AT 250 WORDS)

Acclimatization↗
PubMed1994

Platelet-activating factor acetylhydrolase (PAF-AH) in human kidney.

1. PAF-AH activity in human kidney (cortex and medulla) has been demonstrated and shares the following properties. 2. Does not require the presence of Ca2+ and appears to be different from phospholipase A2. 3. The pH optimum shows a peak at 7-7.4. 4. It is stable for 4 days at -30 degrees C. 5. It is mainly distributed in the microsomal fraction. 6. The apparent Km values of the enzymes of cortex and medulla are 0.553 and 0.207 microM, respectively and distinct from serum PAF-AH (1.439 microM). 7. The apparent molecular weight values are 60,000 and 25,000 for medulla and cortex, respectively and distinct from serum PAF-AH (94,000).

1-Alkyl-2-acetylglycerophosphocholine Esterase↗
PubMed1992

Diversity among tight junctions in rat kidney: glomerular slit diaphragms and endothelial junctions express only one isoform of the tight junction protein ZO-1.

ZO-1 is a 225-kDa peripheral membrane protein present in all tight junctions. It was recently shown to consist of two isoforms that differ in the presence of an internal 80-amino acid domain termed motif-alpha. To obtain information on their distribution and potential functional significance we have localized the two isoforms in rat kidney by using antibodies that recognize either both ZO-1 isoforms or the larger, motif-alpha-containing isoform. By immunofluorescence, staining with both antibodies was demonstrated at all tight junctions of tubular epithelial cells and the epithelial cells of Bowman's capsule. In contrast, the motif-alpha-containing isoform was absent from the slit diaphragms of the glomerular epithelium and the tight junctions of glomerular and peritubular capillary endothelial cells. This restricted isoform expression was confirmed by immunoblot analysis comparing proteins from purified glomeruli with those from kidney cortex or medulla. Thus, while both isoforms are expressed in typical epithelial tight junctions, only a single isoform, lacking motif-alpha, is expressed in the highly specialized slit diaphragms, where the intercellular spaces are normally open, and in endothelial junctions, which are readily opened by physiologic signals. The differential expression of ZO-1 isoforms in structurally and functionally distinct junctions in the kidney suggests that they may contribute to defining the variable functional properties, in particular the lability of these intercellular junctions.

Aging↗
PubMedDate not supplied

Topographic distribution of aquaporin 2 mRNA in the kidney of dehydrated rats.

BACKGROUND: Stimulation of arginine vasopressin results in an immediate redistribution of water channels (aquaporin 2; AQP2) in the apical membrane of the collecting ducts, leading to water reabsorption. Water restriction for >/=24 h increases AQP2 proteins in the whole collecting duct which is highest in the inner medulla of the kidney, indicating that dehydration enhances synthesis of this protein. Although increased expression of AQP2 mRNA under this condition has been reported, the increased ratio of mRNA expression in the three regions of the kidney, cortex, outer medulla, and inner medulla, during the dehydration is still unclear. METHODS: We investigated the AQP2 transcripts using male Sprague-Dawley rats deprived of water for 24 h. Mimic cDNA for competitive polymerase chain reaction (PCR) was constructed by deleting 180 bp at the middle of a 780-bp partial PCR product for rat AQP2 cDNA. In situ hybridization of the kidney and Northern blotting of inner medulla were performed using a 60-bp oligo-cDNA probe which identified rat AQP2 transcripts in the collecting duct. RESULTS: Dehydration resulted in a significant increase in plasma osmolality and arginine vasopressin concentration and urinary osmolality. Competitive PCR demonstrated that dehydration increased AQP2 transcripts in all parts of the kidney, but was highest in the inner medulla. Northern blotting confirmed the high increased rate of AQP2 transcription in the inner medulla. In situ hybridization showed markedly intensified signals in the inner medulla of dehydrated rats. CONCLUSIONS: Our data indicate that dehydration increases the abundance of AQP2 transcripts which may be closely associated with enhancement in AQP2 protein synthesis reported previously. This topographically variable increase in transcription is considered to be one of the mechanisms involved in long-term regulation of water permeability in the collecting duct.

Animals↗
PubMed2006

Maintained ENaC trafficking in aldosterone-infused rats during mineralocorticoid and glucocorticoid receptor blockade.

Aldosterone induces redistribution of epithelial sodium channel (ENaC) to the apical plasma membrane from intracellular vesicles in renal connecting tubule (CNT) and cortical collecting duct (CCD). The role of the classical mineralocorticoid receptor (MR) in ENaC trafficking is still debated. We examined whether the MR antagonist spironolactone affects ENaC regulation in the kidney cortex of aldosterone-infused rats. Aldosterone infusion for 7 days resulted in a plasma aldosterone concentration in the high physiological range (3 to 4 nM). Aldosterone infusion decreased plasma K(+) concentration compared with untreated control rats. Cotreatment with spironolactone completely blocked the aldosterone-induced decrease in plasma K(+). Immunoblotting and immunohistochemistry showed increased protein abundance of Na-K-ATPase alpha(1)-subunit and NCC in the kidney cortex, in response to aldosterone infusion that was blocked by spironolactone. In contrast, aldosterone-induced redistribution of ENaC subunits from the cytoplasm to the apical plasma membrane domain in CNT and CCD was unaffected by spironolactone. Immunoblotting of alphaENaC showed increased protein abundance in aldosterone-infused rats that was not blocked by spironolactone treatment. To exclude possible glucocorticoid receptor (GR)-mediated effects of aldosterone, we treated aldosterone-infused rats with both spironolactone and the GR antagonist RU486. Combined MR and GR blockade prevented neither ENaC trafficking nor the upregulation of alphaENaC protein abundance in aldosterone-infused rats. We provide new evidence for ENaC trafficking occurring independent of MR and GR activation in aldosterone-infused rats.

Aldosterone↗
PubMed1983

Hypothermic perfusion of human kidney carcinoma: effects on viability and perfusate distribution.

A more deteriorating effect on tumour tissue than on normal renal parenchyma by hypothermic perfusion has previously been observed. The purpose of this study was to further evaluate changes in the perfusate distribution and the viability of normal cortical tissue and of kidney carcinoma during hypothermic perfusion. Tumour-involved kidneys obtained by nephrectomy from 12 patients were studied either with regard to viability, as measured with the Na+-K+ pump function in incubated tissue slices, or with regard to perfusate flow, as analysed with an isotope labelled microsphere technique. Six days of hypothermic perfusion decreased the potassium content in the tumour tissue, while it was mainly unchanged in the cortical tissue. The steady-state level of potassium in incubated slices reflected that the transmembrane K+ influx was unchanged after 6 days of perfusion in normal cortical tissue, whereas a significant reduction was observed in the tumour tissue. The relative perfusate flow in the tumour, when compared to the normal kidney cortex flow, was reduced from 60% after 1 hr of perfusion to 30% after 6 days of perfusion.

Adult↗
PubMed1997

Differential SP220K expression in renal carcinoma and oncocytoma cells.

SP220K is a newly described serine proteinase which displays guanidinobenzoatase activity in its inactive form and gelatinolytic activity in its active form. SP220K expression was studied in 20 renal clear-cell carcinomas and in a series of renal oncocytomas, a rare benign tumor derived from the kidney tubule epithelium. We provide evidence that SP220K expression, as assessed by guanidinobenzoatase activity, gelatin zymography and Western blot immunodetection, was increased markedly in cancer basolateral membranes compared to kidney cortex controls, whereas no signal was detectable in basolateral membranes from the 5 renal oncocytomas studied. Cytoplasms of carcinoma cells were immunodetected consistently, whereas no expression was seen in oncocytic cells from any of the oncocytomas studied (12/12). Endothelial cells were immunodetected in all 3 tissue types. Our data favor a potential mechanistic relationship between expression of the matrix proteinase SP220K and invasive phenotype in kidney epithelium proliferative processes.

Adenoma, Oxyphilic↗
PubMed1997

Inhibition of 11 beta-hydroxysteroid dehydrogenase obtained from guinea pig kidney by some bioflavonoids and triterpenoids.

AIM: To study the inhibitory effect of some bioflavonoids and triterpenoids on 11 beta-hydroxysteroid dehydrogenase (11 beta-OHSD) from guinea pig kidney. METHOD: The 11 beta-OHSD of kidney cortex microsomes in addition of cortisol was incubated in the presence of NADP, Triton DF-18, and the test compounds at 37 degrees C for 1 h. The enzyme activity was assayed by measuring the rate of conversion of cortisol to cortisone eluted with HPLC gradient analysis. RESULTS: The IC50 (95% confidence limits) values of glycyrrhizic acid, naringenin, fisetin, emodin were 254 (202-320), 336 (270-418), 470 (392-564), and 527 (425-653) mumol.L-1, respectively. The inhibitory effect of oleanolic acid was 2-fold stronger than that of astramembranin I. The mode of action of naringenin was competitive inhibition. CONCLUSION: The test compounds inhibited the 11 beta-OHSD in kidney cortex with different potencies as glycyrrhizic acid did.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1984

A 2'guanidyl derivative of gentamicin (S86451) with reduced nephrotoxicity studies at low and medium dose levels in the rat.

The nephrotoxic potential of S86451 (2'guanidyl, 2'deamino gentamicin C1) has been investigated in Sprague-Dawley rats at 10 and 25 mg/kg, in comparison with gentamicin at 4 and 10 mg/kg. The criteria were (i) the severity of the lysosomal phospholipidosis, as assessed by both biochemical and morphological investigations; (ii) the degree of tubular regeneration, a consequence of the aminoglycoside-induced focal necrosis measured by 3H-thymidine incorporation into kidney cortex DNA. S86451 was found at least 2-5 times less toxic than gentamicin. Thus, this compound should be a safer antibiotic than gentamicin in combating organisms with a similar sensitivity to either drug.

Animals↗