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PubMed1993

Light microscopic radioautographic study of DNA synthesis in the kidneys of aging mice.

The change of proliferative activity in mouse kidney cortex cells during development and aging was studied by detecting S-phase cells by light microscopic radioautography using 3H-thymidine (3H-TDR). Mouse kidney tissues of various ages: prenatal 13.5, 15.5 and 19.0 days of gestation, postnatal 1 and 8 days, 1 and 2 months, and 1 year were used for this experiment. The kidney cortex tissues were labelled with 3H-TDR either in vitro or in vivo and they were processed for light microscopic radioautography. The labeling indices of the respective cell types were calculated. The labeling indices in glomeruli and uriniferous tubules in the superficial layer were higher than those in the deep layer of metanephric cortex through the developmental stages. However, they decreased rapidly after birth and reached low levels (below 4%) from 1 day to 1 year.

Aging↗
PubMed1981

Na+-stimulated ATPase activities in kidney basal-lateral plasma membranes.

In the present work we demonstrate the existence of a Na+-dependent ATPase activity, which is insensitive to ouabain, and which is 100% inhibited by 1.5 mM ethacrynic acid in freshly prepared, basal-lateral enriched, plasma-membrane fractions obtained from guinea-pig kidney cortex slices (which are mainly made up by proximal tubules). This ATPase activity has characteristics similar to those described previously in a microsomal fraction of the guinea-pig kidney cortex by a procedure which required ageing of the preparation for more than two weeks (Proverbio, F., Condrescu-Guidi, M. and Whittembury, G. (1975) Biochim. Biophys. Acta 394, 281-292), it does not seem to be due to some partially modified activity of the Mg2+-ATPase, the (Na+ + K+)- or the Ca2+-ATPase activities present in this tissue. It seems to be due to the activity of another system, which is located on the basal-lateral membrane of the kidney tubular cells.

Adenosine Triphosphatases↗
PubMed1998

Kidney ectopeptidases in gentamicin and mercuric chloride-induced acute renal failure.

The clinical use of gentamicin is associated by nephrotoxicity in over 10% of patients. However, the biochemical events responsible for proximal tubular injury and acute renal failure (ARF) are still unclear. In the present study, effects of gentamicin and, comparatively, of mercuric chloride upon rat kidney cortex ectopeptidases were studied. Gentamicin was given i.p., 100 mg/kg daily for up to 6 days, mercuric chloride i.p. once 2.5 mg/kg to rats studied after 3 days. Kidney cortex aminopeptidase N decreased significantly after 3 and 6 days' treatment (p < 0.01), however, angiotensinase A significantly decreased after 3 (p < 0.01), and much more after 6 days of gentamicin treatment (p < 0.001). Dipeptidylpeptidase IV activity was significantly decreased only after 6 days of treatment with gentamicin. In mercuric chloride-induced ARF all three peptidase activities were markedly decreased (p < 0.001). These results suggest that gentamicin-induced decrease in ectopeptidase activities could compromise vasoactive and other biologically active peptides handling, with important consequences upon renal function and metabolism.

Acute Kidney Injury↗
PubMed2003

Dietary citrate treatment of polycystic kidney disease in rats.

Progression of autosomal-dominant polycystic kidney disease (ADPKD) in the heterozygous male Han:SPRD rat is dramatically slowed by ingestion of potassium or sodium citrate. This study examined the efficacy of delayed therapy with sodium citrate, the effect of sodium citrate therapy on kidney cortex levels of transforming growth factor-beta (TGF-beta), and the response to calcium citrate ingestion. Rats were provided with citrate salts in their food, and renal clearance, blood pressure, blood chemistry, and survival determinations were made. Sodium citrate therapy was most effective when started at age 1 month, and delay of therapy until age 3 months produced no benefit. Kidney cortex TGF-beta levels were elevated in 3- and 8-month-old rats with ADPKD, but not in 6-week-old rats. Sodium citrate treatment, started at age 1 month, lowered TGF-beta levels to normal in 3-month-old rats, but this is probably not the primary mechanism of citrate's beneficial effect. Calcium citrate had only a modest effect in preserving glomerular filtration rate. Effective treatment of ADPKD in this rat model requires early administration of a readily absorbed alkalinizing citrate salt. Existing data on ADPKD patients on vegetarian diets or with kidney stones should be studied in light of these findings.

Animals↗
PubMed1992

Interaction of cadmium with atrial natriuretic peptide receptors: implications for toxicity.

Atrial natriuretic peptide (ANP) is a diuretic and vascular smooth muscle relaxant which plays a pivotal role in cardiovascular regulation. Since cadmium (Cd) produces cardiovascular toxicity and alters ANP levels in atria and hypothalamus, its effect on ANP receptors were studied in rats and in PC12 cells exposed to Cd. Male rats were injected with CdCl2 (0.01, 0.1, 0.5 or 1.0 mg/kg, i.p.) twice a day for 7 days and then maintained for a period of 30 days. On experimental day 37 ANP receptor binding in the adrenal cortex, aorta and kidney cortex was studied by saturation isotherm analysis. In Cd-treated animals a non-dose related decrease in receptor affinity and density was observed in the kidney and aorta with the aortic ANP receptors being the most sensitive. Cellular regulation of the receptor was studied in PC12 cells, a cell line that expresses functional ANP receptors. Incubation of PC12 cells with Cd reduced both the affinity of the receptor for ANP and decreased the number of binding sites on the cell plasma membrane. The ratio of ligand-receptor complex internalized in the cell to ligand bound to the plasma membrane was significantly decreased following Cd pretreatment (500 microM). A significant decrease in the internalization rate of [125I]ANP was observed in cells incubated concurrently with Cd and ligand. In photoaffinity labelling studies with [125I]ANP, binding of ANP to B and C receptors subtypes was decreased following treatment of either intact cells or plasma membranes with Cd. It was concluded that Cd produces significant alterations in the ANP receptor, both in in vitro and in vivo models and it is proposed these effects play a role in the cardiovascular toxicity of this heavy metal.

Animals↗
PubMed1991

Subcellular localization of celiptium-induced peroxidative damage in rat renal cortex.

Celiptium (N2-methyl-9-hydroxyellipticinium) is an antitumor agent of the ellipticine series. We have shown a dose-dependent nephrotoxicity in rats and demonstrated a lipid overload in proximal tubular cells (unsaturated free fatty acid accumulation). We have also shown an increase in thiobarbituric acid reactive substances (TBARS), namely the 4-hydroxyalkenals, that is paralleled by a decrease in phosphatidylethanolamine in rat kidney cortex. In the present study, peroxidative damage was localized in mitochondria, microsomal and brush-border membranes of kidney cortex. Female Wistar rats were injected with a single i.v. dose of 20 mg/kg celiptium and sacrificed on day 8. Subcellular fractionation studies showed that celiptium induced alterations: 1) in mitochondria (slight increase in aldehydes), 2) in microsomal membranes (increase in free fatty acids (FFA) with in particular rises in oleic (18:1) and linoleic (18:2) acids), 3) in brush-border membranes or BBM (decrease in protein and phospholipid contents); residual membranes showed an increase in oleic and linoleic acids and a decrease in the polyunsaturated fatty acids, arachidonic (20:4) and docosahexaenoic (22:6) acids, 4) in cytosol (increase in FFA and TBARS content). Thus, celiptium induces peroxidative damage in kidneys through lipid abnormalities which predominantly occur in brush-border membranes and consist of an increase in free fatty acids and aldehydes in cytosol.

Animals↗
PubMed1997

Recognition of tissue- and subtype-specific modulation of angiotensin II receptors using antibodies against AT1 and AT2 receptors.

Polyclonal antibodies have been prepared against synthetic peptides of human angiotensin II type-1 (AT1) and type-2 (AT2) receptors. Synthetic peptides corresponded to amino acids 15-24 of AT1 receptor and amino acids 241-253 of AT2 receptor. Western blot analysis of membranes from cell homogenates of COS-7 cells transfected with expression plasmids for mouse AT1b receptor, human vascular smooth muscle cells, and rat peripheral tissue demonstrated a major band of MW 44,000 with AT1 receptor antibody. Cell homogenates of COS-7 cells transfected with expression plasmids for human AT2 receptor showed a band of MW 44,000 with AT2 receptor antibody. Tissue homogenate of rat adrenal medulla and human pheochromocytoma presented a major band of MW 52,000 and a minor band of MW 44,000 with AT2 receptor antibody. AT1 receptor expression was in the following order: rat aorta > > lung, kidney, spleen, adrenal cortex > adrenal medulla, heart. Expression of AT2 receptor was in the following order: rat adrenal medulla > cortex, kidney, heart. Three-day treatment with CS866, an AT1 receptor antagonist, and temocapril, an angiotensin-converting enzyme inhibitor, suppressed AT1 receptor expression in the rat adrenal cortex, but not in the heart or adrenal medulla. AT2 expression was not affected by treatment with these drugs. These results suggest that newly developed antibodies for AT1 and AT2 receptors are useful in elucidating the regulation of subtype-specific receptor expression, and that AT1 but not AT2 receptors in adrenal tissue are regulated by angiotensin II.

Adrenal Glands↗
PubMed1992

Altered renal dopamine receptors during development of cardiac hypertrophy.

The characteristics of dopamine receptors were studied in heart and kidney using the radiolabeled receptor assay of [3H]spiperone during the development of cardiac hypertrophy. Male Sprague-Dawley rats (175-200 g) underwent abdominal aortic constriction above the renal arteries and were studied 3, 14, and 28 days thereafter. Sham-operated animals without aortic constriction were used as control. Although the ratio of left ventricular weight to total body weight was significantly increased 14 and 28 days after aortic constriction in animals, [3H]spiperone binding in left ventricular membrane was increased as early as 3 days after aortic constriction. At 14 days, the binding was still elevated and, by 28 days, it returned to control values. In contrast, membranes obtained from kidney cortex showed an elevation of [3H]spiperone binding only at 28 days after aortic constriction; at 3 days the binding values were decreased. A reciprocal correlation was found between the number of dopamine receptors and the activity of Na(+)-K(+)-ATPase at 28 days of aortic constriction; the enzyme activity, as measured by the release of 32Pi from [gamma-32P]ATP, was decreased in kidney cortex. Autoradiographic data also showed an increased number of dopamine receptors in kidney at 28 days after abdominal aortic constriction. These results suggest that the dopamine receptor is increased very early in heart in response to pressure overload as a result of a compensatory response to maintain an optimal left ventricular output. Kidney dopamine receptors are triggered at a later stage possibly to maintain fluid homeostasis secondary to the cardiac hypertrophic process.

Animals↗
PubMed1986

[Age and features of prostanoid biosynthesis in the rat kidney].

The biosynthesis of PgF2, 6-keto-PgF1 alpha and TxB2 from endogenous precursor in vitro by the rat kidney cortex and medulla in ontogenesis was found to be highest at young age reducing from papillae to kidney cortex. The main product of the biosynthesis in kidney medulla of young and adult rats was PgE.

Animals↗
PubMed1993

Mercury contents of indicators and target organs in rats after long-term, low-level, mercury vapor exposure.

Five groups of Wistar rats received graded concentrations of mercury vapor from 10 to 100 micrograms Hg/m3 6 hr, 5 days a week, from 4 to 11 weeks of age. One group breathing ambient air served as controls. The mercury levels of the indicators blood, hair, molars, and incisors as well as the target organs kidney cortex, cerebrum, cerebellum, liver, lung, spleen, tongue, and femur were measured by cold-vapor atomic absorption spectrophotometry. The mercury vapor had no negative influence on the weight gain of the animals. The results showed that the kidney cortex had the highest concentration of mercury. The mercury contents of all the indicators and all the target organs, with the exception of femur, were positively and significantly correlated with the exposure concentration. The rat molars had the highest correlation coefficient with the kidney mercury values, but no indicator had a significant correlation with all target organs. Rat molars are to some degree comparable to human deciduous teeth regarding time of mineralization and eruption. Based on the results presented in this study, we tentatively suggest that human deciduous teeth can be useful indicators of chronic mercury exposure not only at the exposure concentration level, but also as indicators of the mercury uptake in organs such as kidney and cerebrum.

Animals↗
PubMed1981

Cadmium in man measured in vivo by x-ray fluorescence analysis.

The sensitivity and detection limit for measurements of the concentration of cadmium in the kidney cortex of man in vivo have been investigated using the technique of X-ray fluorescence. An 11 GB1 241Am source was used to generate the characteristic K alpha X-rays of cadmium. The variation in the sensitivity for the detection of cadmium at various locations in a kidney has been studied. Because of the pronounced variation in sensitivity with depth in tissue, a measurement could be made selectively in the kidney cortex. The minimum detectable Cd concentration varies between 20 and 40 micrograms g-1 for distances between the skin and the kidney surface of 30 to 40 mm; this distance has a measured uncertainty of +/- 3 mm which gives rise to an uncertainty of +/- 30% in the estimated Cd concentration. The mean absorbed dose to the kidney during such a measurement is about 0.6 mGy. The X-ray fluorescence method is more advantageous than the alternative neutron capture gamma ray analysis technique as far as the total irradiation of the patient is concerned. The cadmium concentrations in the kidneys of five exposed persons were found to lie between 30 and 143 micrograms g-1.

Cadmium↗
PubMed1987

Regulation of inactive renin secretion: studies with aprotinin.

The kidney and plasma of many species contain both an active form of renin and an inactive, but activatable, form. The kallikrein inhibitor aprotinin suppressed acid-activation of rabbit plasma inactive renin but not activation of the form of inactive renin released by rabbit kidney cortex slices incubated in vitro. This suggests that inactive renin is structurally modified after secretion. An aprotinin-sensitive step appears to regulate inactive renin secretion. Aprotinin inhibited inactive, but not active, renin secretion by rabbit kidney cortex slices and selectively suppressed the elevated release of inactive renin produced in sheep by the converting enzyme inhibitor enalapril. In anaesthetised rats, aprotinin potentiated the increase in plasma renin produced by captopril.

Animals↗
PubMed2006

Acute and long-term effects of clinical doses of antenatal glucocorticoids in the developing fetal sheep kidney.

OBJECTIVES: The controversy regarding potential long-term side effects of antenatal steroid administration for accelerating fetal lung maturation is still unresolved despite more than 30 years of experience. Studies in animals have demonstrated that administration of glucocorticoids during pregnancy alters renal expression of several key regulatory molecules at different developmental stages followed in most cases with the development of hypertension in the adult. We studied the effects of betamethasone on the expression of (1) NA,K-ATPAse pump; (2) the Na/H exchanger 3 (NAHE3); (3) angiotensin receptor (AT1 and AT2); and (4) the type 1 dopamine receptor (D1R). METHODS: Pregnant sheep were treated with either 0.17 mg/kg betamethasone or vehicle 24 hours apart at 80 and 81 days' gestation. Fetal kidneys were harvested at 81 and 135 days' gestation. Protein and mRNA levels were measured in kidney cortex. RESULTS: Betamethasone had acute and long-term effects on fetal kidney cortex gene expression. Acutely, mRNA abundance for AT2 was significantly lower and that of NHE3 significantly higher than in controls (0.4 +/- 0.02 vs 0.7 +/- 0.05; 1.2 +/- 0.16 vs 0.4 +/- 0.04; P < .05). At 135 days' gestation, AT2 receptor abundance remained lower than control (0.2 +/- 0.02 vs 0.4 +/- 0.02; P < .05), whereas D1R expression was higher (0.8 +/- 0.17 vs 0.5 +/- 0.06; P < .05). No changes in Na,K-ATPase of AT1 receptor at either of the two time points studied were observed. Antenatal steroid administration was not associated with premature labor or a reduction in either body weight or kidney weight. CONCLUSION: Our findings strongly suggest that antenatal glucocorticoid administration according to National Institutes of Health (NIH) consensus guidelines may alter human fetal renal development. Further studies are needed to establish a direct relationship between alterations in fetal renal gene expression and the development of hypertension in adulthood.

Animals↗
PubMed1976

On the mechanism of malonyl-CoA-independent fatty-acid synthesis. Different properties of the mitochondrial chain elongation and enoylCoA reductase in various tissues.

1. NADPH-specific mitochondrial enoyl-CoA reductase can be assayed by a sensitive radioactive test, employing tritium-labelled NADPH, synthesized in a prefixed reaction from D-[1-3H]-glucose via the hexokinase and glucose-6-phosphate dehydrogenase reactions. 2. Liver, kidney cortex, heart muscle, skeletal muscle, brown adipose tissue, brain cortex, and aortic intimal tissue are investigated concerning chain lengths specificity of the chain elongation and the enoyl-CoA reductase. Medium-chain acyl-CoA compounds prove to be the best primers for the chain elongation. Enoyl-CoA reductases still show large incorporation rates with hexadecenoyl-CoA. 3. The differences in the chain lengths specificity of the chain elongation and enoyl-CoA reductase can be explained by the inhibitory effect of long-chain acyl-CoA derivatives on the 3-hydroxyacyl-CoA dehydrogenase. 4. The nucleotide specificity in the different tissues reveals two types of chain elongation: In addition to liver and kidney cortex, mitochondria of brown adipose tissue need NADH + NADPH for optimal chain elongation, whereas heart muscle, skeletal muscle and aortic intimal mitochondria only need NADH. 5. Different physiological roles are proposed for the two types. The "heart type" may be of importance in the conservation of reducing equivalents or acetate units in the anaerobic state, the "liver type" may play a role in the transfer of hydrogen from NADPH to the respiratory chain. In addition, the mitochondrial chain elongation may serve as bypass of the first part of the respiratory chain.

Adipose Tissue, Brown↗
PubMed2006

Evaluations of the renal cell carcinoma model Caki-1 using a silicon based microvascular casting technique.

The vascular development of orthotopically grown human renal cell carcinoma (Caki-1) was examined using a silicon based casting technique in nude mice. Images taken of these vascular casts showed Caki-1 tumors to be highly vascularized and invasive. The spread of the tumor within the cortex of the kidney revealed that Caki-1 recruits the kidney's own vasculature, destroying the functional glomeruli in the process. The loss of these glomeruli was further highlighted by the presence of enlarged glomeruli resulting from the development of super nephrons. Vessel size and density measurements were then made in this model. This was done using both computer-based and manual measurement methods. In the vessel size studies the computer-based method tended to overestimate the number of larger diameter vessels whereas the vessels density assessment showed good agreement between the two techniques. Nevertheless, both methods showed that Caki-1 tumors possessed a higher proportion of larger diameter vessels and a lower vessel density than normal kidney cortex. In summary, silicon based vascular casting proved to be a simple and effective tool for the study of tumor vasculature. In particular this technique could readily be used to examine the invasion of tumor into normal tissue. The computer-based technique for evaluating vessel number and vascular density was found to have merit in both normal and tumor tissues, particularly in the vascular density studies. However, in both settings this technique did tend to overestimate the number of larger diameter vessels.

Animals↗
PubMed1993

Role of a basement membrane glycoprotein in anti-tubular basement membrane nephritis.

Tubulointerstitial nephritis antigen (TIN antigen) is a basement membrane component which is recognized by human autoantibodies in TIN and has been shown to induce TIN in Brown Norway (BN) rats. Detectable by immunofluorescent microscopy, TIN antigen reacts with monoclonal, polyclonal, and human autoantibodies in basement membranes of kidney cortex, small intestine, skin and cornea. Specific sites of TIN antigen within kidney cortex include basement membranes of proximal tubules, distal tubules, Bowman's capsule and peritubular capillaries, with highest concentration in proximal tubular basement membrane (TBM). TIN antigen is also present in interstitium between tubules and in the periarterial sheath, but not in glomerular basement membrane or mesangial matrix. Immunoblotting of TIN antigen isolated from rabbit TBM reveals a major 58 kDa component with minor components of 300 kDa, 175 kDa, 160 kDa, 100 kDa and 50 kDa. Partial protein sequence analysis indicates that 58 kDa TIN antigen represents a newly defined glycoprotein. The structural relationships between various molecular weight forms are currently being investigated. High molecular weight (HMW) forms of TIN antigen, consisting of a mixture of 300 kDa, 175 kDa and 160 kDa forms, are more efficient than low molecular weight (LMW) forms (58 kDa and 50 kDa forms) in inducing TIN in BN rats. The resultant antibody specificity of rats injected with either HMW TIN antigen or LMW TIN antigen is identical as determined by immunofluorescent microscopy and Western analysis. Higher antibody titers and greater amounts of kidney-bound IgG are found in the HMW TIN antigen-immunized animals. TIN antigen is the primary target of anti-TBM antibodies in human and experimental immunologically-mediated anti-TBM nephritis.

Animals↗
PubMed2001

Expression and induction of cytochrome P450s in rabbit parotid glands.

Earlier, we isolated and purified five different P450 isoforms from rabbit kidney cortex microsomes, three of which are members of the CYP4A subfamily (CYP4A5, CYP4A6, and CYP4A7), with the others being CYP2B4 and CYP1A1. In contrast, P450s in parotid glands were unknown. The fact that the parotid glands bear a marked morphological and functional resemblance to kidney tissue prompted us to investigate P450s in these glands. The present study was undertaken to determine which P450 isoforms are expressed in this tissue. Microsomes from parotid glands of untreated rabbits were found to contain 42.3 pmol of P450/mg protein and to catalyze the omega-hydroxylation of laurate. Administration of di(2-ethylhexyl) phthalate (DEHP) resulted in a 7-fold increase of laurate omega-hydroxylation. This enzyme activity was greatly inhibited by pretreatment with antibodies against CYP4A5. Furthermore, parotid gland CYP4A5, CYP4A6, and CYP4A7 mRNAs were identified by RT-PCR. Moreover, the CYP4A enzymes were demonstrated immunohistochemically to be localized exclusively in the ducts of these glands. In addition to the CYP4A enzymes, immunoblot analysis revealed that CYP2B4 is constitutively present, and that CYP1A1 is induced in these glands by treatment with 3-methylcholanthrene. Taken together, we can conclude that the P450 isoforms expressed in rabbit kidney cortex and parotid glands are identical in composition.

Animals↗