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PubMed1997

Expression of carbonic anhydrase IV mRNA in rabbit kidney: stimulation by metabolic acidosis.

The renal carbonic anhydrases, CA II (cytosolic) and CA IV (membrane bound), are believed to facilitate renal acid secretion. We have recently shown that renal cortical sodium dodecyl sulfate (SDS)-resistant hydratase (presumably CA IV) activity was stimulated 241% during chronic metabolic acidosis (CMA). In the present study, we examined the expression and regulation of CA IV mRNA in kidneys from control and acidotic rabbits. To obtain a CA IV probe, we reverse transcribed rabbit kidney total RNA and amplified a approximately 780-base pair (bp) DNA product using primers derived from the human CA IV sequence. Using this product, we screened one-half of a kidney cortex cDNA library and sequenced a 1,194-bp cDNA, which contained the entire open-reading frame of rabbit CA IV. The cDNA was 78% identical to human and 71% to rat CA IV. The deduced amino acid sequence projected an active zinc binding site and two glycosylation sites. Northern analysis yielded a single transcript of approximately 1,600 bp in size expressed more abundantly in cortex and inner medulla than in outer medulla. CA IV mRNA was also expressed abundantly in lung but not in liver or spleen. The high abundance of CA IV mRNA in inner medulla was localized by in situ hybridization to medullary collecting duct cells. Rabbits exposed to CMA showed significant upregulation of CA IV mRNA expression in kidney cortex and outer medulla. Despite a numerical increase, excessive variability precluded statistical significance in the inner medulla. Thus CA IV mRNA was expressed abundantly in kidney and stimulated by CMA, similar to what has been previously observed for SDS-resistant hydratase (presumed CA IV) activity. It is likely that the regulation of CA IV mRNA and activity is relevant to the kidney's adaptation to CMA.

Acidosis↗

PubMed1995

Silver concentrations in human tissues. their dependence on dental amalgam and other factors.

Human tissue samples (liver, kidney cortex, 5 brain regions: grey matter of cerebrum, white matter of cerebrum, nucleus lentiformis, cerebellum, brain stem) from 173 decreased persons were analysed for silver (Ag) by GF-AAS (Graphite Furnace Atomic Absorption Spectrometry) and the results compared with the number of teeth with amalgam fillings and the concentration of inorganic mercury (Hg), which had been determined in the same tissue samples in a previous study. It was found that the mean Ag concentrations in liver and brain of adult females are approximately twice that of males. Moreover, the Ag concentrations, especially in the brain, depend possibly on age. To exclude these confounding factors as far as possible, the influence of dental amalgam and the correlation of Ag and Hg were evaluated only in a sub-group of 93 males, aged 11-50 years. In this sub-group statistically significant correlations were found between the number of teeth with dental amalgam and the Ag concentrations in the cerebral cortex and the liver. No such correlation was found for the kidney. Ag and inorg. Hg correlate well in this sub-group in the liver, but not in the cerebral cortex or the kidney. Individuals from this sub-group with (i) 0-2 and with (ii) more than 9 teeth with amalgam fillings show mean Ag concentrations (micrograms/kg in tissue wet weight, geom. mean) of 1.59 and 5.41 in the grey matter of cerebrum, 1.42 and 4.25 in the white matter of cerebrum, 1.53 and 4.89 in the nucleus lentiformis, 1.95 and 5.02 in the cerebellum, 1.05 and 3.27 in the brain stem, 3.40 and 8.15 in the liver and 0.42 and 0.44 in the kidney cortex. In contrast, comparing all individuals under investigation with only 0-2 teeth with amalgam no correlation between Ag and inorg. Hg could be found in liver, kidney cortex or cerebral cortex. These results show that amalgam fillings release Ag as well. Considering the different toxicokinetics of Ag and Hg it can be concluded that Ag is a reliable marker for the fact that the elevated concentrations of inorg. Hg found in tissues of individuals with amalgam fillings derive mainly from these fillings and not from other theoretically possible sources.

Adolescent↗

PubMed1979

Succinate dehydrogenase activity in rat kidney after repeated administrations of p-aminohippurate or sodium chloride.

During PAH excretion and 18 h after repeated PAH administrations to rats, renal cortical SDH activity was unchanged in comparison with untreated controls. On the other hand, 18 h after repeated administrations of 0.9% or 1.8% NaCl solution, SDH activity was decreased by about 20% in kidney cortex. In outer medulla SDH activity was decreased 18 h after all pretreatments. The decline of SDH activity was observed whenever an increased urinary Na excretion occurred, except that PAH was repeatedly administered. The probability is discussed that substrate-induced stimulation of the carrier system for weak organic acids is accompanied by an increase of mitochondrial activity in kidney cortex.

Aminohippuric Acids↗

PubMed1984

[Distribution of various sites of hormonal action between microvessels, glomeruli and tubules isolated from the renal cortex of rabbits].

Collagenase dispersion of rabbit kidney cortex followed by centrifugation on discontinuous sucrose gradient, allowed the simultaneous obtention of microvascular, glomerular and tubular fractions. Microscopic studies and the measurements of cellular renin activity and the muscle-specific-enzyme creatine kinase showed that these vessels were arteriolar in nature and that they contained the preglomerular arterioles. The glomerular or tubular contamination rates were assessed by means of enzymatic markers. AVP stimulated only the tubular fraction whether GTP was present or not. In the absence of GTP, beta-isoproterenol stimulated only the tubular enzyme while in the presence of GTP, the microvascular and especially the glomerular AC were also stimulated. GTP enhanced considerably the microvascular response to bPTH-(1-34) while, in the glomeruli and tubules the effects of GTP and hormones were only additive. The possible physiological significance of these results are discussed.

Animals↗

PubMedDate not supplied

Apoptosis of rat kidney cells after 241-americium administration.

Tumors induction by americium is well known but there are no data on the biological effects of this radionucleide at subcellular level. In order to study the possible ultrastructural lesions induced by this element, a group of rats were injected with 241-Americium-citrate (9 kBq), once a week for five weeks and sacrificed 7 days after the last injection. We describe the alterations observed in the cortex kidney using cytochemical (TUNEL reaction) and histochemical (PAS staining) methods for light microscopy as well as electron microscopy techniques. Various types of lesions were detected: condensation of nuclear chromatine, fragmentation of the nuclei, swollen mitochondria, disappearance of mitochondrial crests and skrinking of the cytoplasm. This study clearly demonstrated the induction of apoptosis by americium in rat cortex kidney cells.

Americium↗

PubMed1979

Effect of thyroidectomy upon the activity of three mitochondrial shuttles in rats.

The activities of mitochondrial alpha-glycerophosphate, malate-asparte, and malate-citrate shuttles which oxidize NADH were determined in liver and kidney cortex mitochondria isolated from Tx and control rats. Weight gain, relative liver and kidney size, oxygen consumption, and serum thyroxine were also determined. Tx animals weighed less, had smaller livers and kidneys, and showed significantly lower oxygen consumption of the resting animal and a marked decrease in serum thyroxine levels. The activity of the three shuttles studies was significantly less in liver mitochondria from Tx animals, particularly when studied in the absence of added ADP. Thyroidectomy had less effect upon shuttle activity of mitochondria from the kidney cortex, with significant decrease in activity found only in the complete alpha-glycerophosphate shuttle and in the endogenous malate-aspartate and malate-citrate shuttles studied in the absence of ADP. Changes in shuttle activity caused by thyroid hormone are discussed in relation to other known metabolic effects of thyroxine, and the possible primary role of adenine nucleotide translocase activity in mediating other thyroxine-dependent metabolic changes is considered.

Adenosine Diphosphate↗

PubMed1998

Enalapril increases antioxidant enzyme activity in renal cortical tissue of five-sixths-nephrectomized rats.

In rats with five-sixths nephrectomy (remnant kidney), blood pressure, glomerulosclerosis, and proteinuria are significantly reduced by administration of the angiotensin-converting enzyme inhibitor enalapril, during 16 weeks after reduction of the nephron number. The activity of catalase in remnant-kidney cortex homogenate is not influenced by enalapril treatment; the activities of superoxide dismutase and glutathione peroxidase are significantly increased. Elevated lipid peroxidation in cortex homogenates, evaluated by malondialdehyde and 4-hydroxynonenal concentrations, is not changed by treatment. Supplementation of dietary vitamin E to enalapril treatment does not alter antioxidant enzyme activities when compared to enalapril monotherapy. These results show that enalapril improves the balance between reactive oxygen intermediates and antioxidant enzymes in the remnant-kidney cortex of the rat. This finding may in part explain the protective effect of angiotensin-converting enzyme inhibitors on the progression of glomerulosclerosis.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed1984

The effect of streptozotocin-induced diabetes mellitus on urinary excretion of sodium and renal Na+-K+-ATPase activity.

Renal sodium handling and microsomal Na+-K+-ATPase activity in kidney cortex, medulla and papilla of rats with streptozotocin-induced diabetes mellitus (DM) was studied. During 7 days following the administration of streptozotocin GFR, urinary excretion, filtered load and tubular reabsorption of Na+ averaged (mean +/- SE) 1.18 +/- 0.016 ml/min, 1.74 +/- 0.14, 177.3 +/- 8.9 and 175.6 +/- 8.9 mEq/min respectively in experimental rats as compared to corresponding rates of 0.85 +/- 0.04 (P less than 0.001), 0.85 +/- 0.03 (P less than 0.001), 129.8 +/- 5.8 (P less than 0.001) and 129 +/- 5.8 (P less than 0.001) respectively in the control rats. The activity of microsomal Na-K-ATPase in the kidney cortex, medulla and papilla of the control group was (mean +/- SE) 44.7 +/- 1.7, 150 +/- 7.5 and 37.4 +/- 3.6 (mumoles Pi/mg prot/h) respectively. 24 h after DM induction Na-K-ATPase activity in the cortex rose to 59.3 +/- 2.4 (P less than 0.001) and remained high after 3 and 7 days. Medullary Na-K-ATPase activity was unchanged 24 h after streptozotocin administration but was markedly increased to 260 +/- 9 (P less than 0.001) after 3 days and remained high after 7 days. These findings show that streptozotocin-induced DM in rats causes a substantial increase in GFR which is associated with a net increase in filtered and reabsorbed load of Na+ and natriuresis. These alterations are accompanied by a marked increase in Na-K-ATPase activity in renal medulla and in the cortex.

Absorption↗

PubMedDate not supplied

In vitro culture of the proximal tubule of the bovine nephron : the fate of the histiospecific antigens and neosynthesis of an alpha-foetoprotein.

The isolation of pure tubules of the outer cortex of the foetal bovine kidney, using a previously described methods, has shown that the tubule suspension obtained is almost entirely constituted of proximal tubule fragments. The proximal cells obtained from this suspension were grown in vitro. The previously called "nephrospecific" antigens NS1-2 were shown to be strictly specific for the cells of the proximal tubule, which is an "histion" of the kidney, that is to say an ultimate unit of differentiation of this organ. The fate of these antigens, henceforth termed "histiospecific antigens" (of the proximal tubule), was followed in primary monolayer cultures of the proximal tubules, using immunodiffusion tests and immunofluorescence. A rapid decrease in this antigen content of the cells was observed during the in vitro culture. An immunoautoradiographic study demonstrated that the synthesis of these antigens was switched off in the confluent cultures. A similar autoradiographic study demonstrated that these same proximal cells at confluence synthesized a bovine alpha1-foetoprotein, which had been detected in earlier studies of kidney cortex cultures. This double antigenic shift is correlated with the in vitro evolution of some morphological markers of the proximal cells, as studied with the transmission and the scanning electron microscope. The factors responsible for these results are discussed.

Animals↗

PubMed1993

Modification of the glyoxalase system in streptozotocin-induced diabetic rats. Effect of the aldose reductase inhibitor Statil.

The glyoxalase system was characterized in tissue (liver, skeletal muscle, kidney cortex and medulla, lens and sciatic nerve) and blood from streptozotocin-induced diabetic rats and normal controls. The effect of the aldose reductase inhibitor, Statil [3-(4-bromo-2-fluorobenzyl)-4-oxo-3H-phthalazine-1-yl-acetic acid; ICI 128 436], was also investigated. Glyoxalase I and glyoxalase II activities were decreased in the liver and increased in skeletal muscle of diabetic rats and of Statil-treated diabetic rats, relative to normal controls. The concentration of non-protein sulphydryl (NPSH) was decreased in the liver and lens of diabetic rats, relative to normal controls; Statil prevented these effects. The concentrations of methylglyoxal in the kidney cortex and medulla, lens and blood were increased in diabetic rats, relative to normal controls. Statil prevented these increases except in the kidney cortex. The concentration of D-lactate was increased in the lens and blood of diabetic rats, relative to normal controls, which was partially prevented in blood but not in the lens by Statil. These data suggest that the glyoxalase system is modified in tissues and blood of streptozotocin-induced diabetic rats and some of the modifications may be prevented by Statil. The increased concentrations of methylglyoxal in the kidney, lens and blood, and the decreased concentration of NPSH in the lens may be related to the development of diabetic complications.

Aldehyde Reductase↗

PubMed1990

Microvascular perfusion and resistance in extracorporeal cardiopulmonary bypass under hypothermia with high-dose narcotic anesthesia--animal model.

Microvascular perfusion of the liver, kidney (cortex and medulla), pancreas and spleen was measured by laser-Doppler flowmetry under hypothermia in extracorporeal cardiopulmonary bypass, to determine the effectiveness of high-dose fentanyl in improving the microcirculation of these visceral organs. Twenty-four mongrel dogs in two groups were monitored by arterial catheter, Swan-Ganz catheter and laser-Doppler flowmeter. Cardiopulmonary bypass was carried out to induce hypothermia to 20 degrees C through the cannulation of inferior vena cava and aorta. Microvascular perfusion was measured by either needle or suturable probes of laser-Doppler flowmeter in liver, kidney (cortex and medulla), pancreas and spleen. With high-dose of fentanyl (100 micrograms/kg), decrease of microvascular perfusion in liver, pancreas and kidney (cortex and medulla) was less than the control group, especially at 20 degrees C. Notably, the trend of these changes had its unique pattern in each organ due to their own specific anatomical and physiological characteristics, while spleen did not show significant difference in both groups. In summary, high-dose of fentanyl improved the hepatic, renal and pancreatic microvascular perfusion, in agreement with our previous observation, might protect the function of these visceral organs from the damage of microvascular ischemia under hypothermia in the extracorporeal cardiopulmonary bypass.

Anesthesia↗

PubMed2002

11beta-hydroxysteroid dehydrogenase type 2 is expressed in the human kidney glomerulus.

Our previous study demonstrated that the GR is expressed in the human kidney glomerulus. The function of the GR of glomerular cells might be affected by the concentration of intracellular glucocorticoids, which is modulated by 11beta-hydroxysteroid dehydrogenase type 2 (11betaHSD2). Because the expression of 11betaHSD2 in the glomerular cells remains unclear, we used competitive RT-PCR and immunoblotting to detect the expression of 11betaHSD2 mRNA and protein in isolated human glomeruli, in whole kidney cortex as a positive control, and in a human glomerular visceral epithelial cell line. 11betaHSD2 mRNA was detected in all samples. Specific antihuman 11betaHSD2 antibody recognized a single band at 41 kDa, consistent with the molecular mass of human 11betaHSD2, in the samples of the isolated glomeruli and whole kidney cortex. Furthermore, definite 11betaHSD2 enzymatic activity was also determined with the sample of isolated glomeruli. We also performed immunohistochemistry by light and electron microscopy to determine the cellular and subcellular localization of 11betaHSD2 in the human glomeruli. Immunoreactivity of the enzyme was clearly observed in the glomerular visceral epithelial cells and endothelial cells as well as in the distal convoluted tubules and collecting ducts. The subcellular localization of 11betaHSD2 was shown to be endoplasmic reticulum. These results suggest that 11betaHSD2 might play a crucial role in modulating the intracellular concentration of glucocorticoids in human glomerular cells.

11-beta-Hydroxysteroid Dehydrogenase Type 2↗

PubMed2002

Associations between human liver and kidney cadmium content and immunochemically detected CYP4A11 apoprotein.

This present study was undertaken to assess potential effects of cadmium on CYP4A11 apoprotein in human liver and kidney as detected by Western blotting using a highly specific anti-peptide antibody. Liver and kidney cortex samples were autopsy specimens of 37 individuals (26 males and 11 females) whose ages ranged from 3 to 89 years. All were Caucasians who had not been exposed to cadmium in the workplace. Reduced CYP4A11 apoprotein levels were found in chronic hepatitis samples and in liver samples showing fatty changes. In contrast, increased CYP4A11 apoprotein levels were found in liver samples having higher cadmium content compared to the lower cadmium content samples. Increased CYP4A11 levels were also found in liver samples from female donors, compared to male donors; the difference being attributable to higher female liver cadmium burden. In distinction to liver, lowered CYP4A11 levels were seen in the kidney cortex samples which have high cadmium content. It is proposed here that the difference between the absolute cadmium burden of the liver and kidney samples may be responsible for the different patterns of expression of CYP4A11 in these two tissues. Further, since cadmium exposure may be associated with derangement in blood pressure control, it is interesting to note the possible relationship between altered CYP4A11-dependent production of arachidonic acid hydroxy and epoxy metabolites in kidney cortex and altered control of blood pressure. Our findings provide a possible link between these observations.

Adolescent↗

PubMed2002

Regulation of the apical Cl-/HCO-3 exchanger pendrin in rat cortical collecting duct in metabolic acidosis.

Pendrin is an apical Cl(-)/OH(-)/HCO(3)(-) exchanger in beta-intercalated cells (beta-ICs) of rat and mouse cortical collecting duct (CCD). However, little is known about its regulation in acid-base disorders. Here, we examined the regulation of pendrin in metabolic acidosis, a condition known to decrease HCO(3)(-) secretion in CCD. Rats were subjected to NH(4)Cl loading for 4 days, which resulted in metabolic acidosis. Apical Cl(-)/HCO(3)(-) exchanger activity in beta-ICs was determined as amplitude and rate of intracellular pH change when Cl was removed in isolated, microperfused CCDs. Intracellular pH was measured by single-cell digital ratiometric imaging using fluorescent pH-sensitive dye 2',7'-bis-(3-carboxypropyl)-5-(and-6)-carboxyfluorescein-AM. Pendrin mRNA expression in kidney cortex was examined by Northern blot hybridizations. Expression of pendrin protein was assessed by indirect immunofluorescence. Microperfused CCDs isolated from acidotic rats demonstrated approximately 60% reduction in apical Cl(-)/HCO(3)(-) exchanger activity in beta-ICs (P < 0.001 vs. control). Northern blot hybridizations indicated that the mRNA expression of pendrin in kidney cortex decreased by 68% in acidotic animals (P < 0.02 vs. control). Immunofluorescence labeling demonstrated significant reduction in pendrin expression in CCDs of acidotic rats. We conclude that metabolic acidosis decreases the activity of the apical Cl(-)/HCO(3)(-) exchanger in beta-ICs of the rat CCD by reducing the expression of pendrin. Adaptive downregulation of pendrin in metabolic acidosis indicates the important role of this exchanger in acid-base regulation in the CCD.

Acid-Base Equilibrium↗

PubMed1972

3-hydroxybutyrate dehydrogenase in tissues from normal and ketonaemic sheep.

1. In liver, rumen epithelium and kidney cortex of the sheep, a dehydrogenase active against dl-3-hydroxybutyrate occurred in both the cytosol and particulate fractions of the tissues. In brain, heart, skeletal and smooth muscles, the enzyme occurred only in the particulate fraction. 2. Enzyme activity in the cytoplasmic fraction of liver and rumen epithelium was similar with either d(-)-3-hydroxybutyrate or dl-3-hydroxbutyrate, but was less with acetoacetate as the substrate. The cytosol fraction of kidney cortex showed very little activity with d(-)-3-hydroxybutyrate, confirming that most of the activity with dl-3-hydroxybutyrate was with the l(+) isomer in this tissue. 3. 3-Hydroxybutyrate dehydrogenase activities in the cytosol and particulate fractions of liver, rumen epithelium and kidney cortex and in the particulate fraction of brain tissue were not stimulated by phosphatidylcholine, unlike the enzyme in sheep muscle and in tissues of other species. 4. The activity of 3-hydroxybutyrate dehydrogenase was not increased significantly in any of the tissues of ketonaemic sheep. 5. Comparison of rates of 3-hydroxybutyrate production in vivo with the enzyme activity in ketogenic tissue suggested that in sheep the maximum rate of production might be limited by this activity.

Animals↗

PubMedDate not supplied

The subcellular distribution of gold in monkey liver, kidney and spleen, in vivo.

1. The subcellular distribution of gold in the livers, kidney cortex and the spleens of rhesus monkeys was determined at 2, 10 and 20 days after the administration of sodium (195Au)-aurothiomalate. The serum gold levels were also determined over the period of study. 2. With the continued decrease in the serum gold levels from day 1 to day 20, a continued increase in the tissue levels of the organs studied was observed. The corresponding subcellular fractions of the tissues also showed continued increases in the radioactive concentrations of gold. 3. Gold was found to localise in all the organelles of the cells in the liver, kidney cortex and the spleen, though in varying amounts. The largest increases in the concentrations of gold from day 2 to day 20 were found in the lysosomal bodies of liver and kidney. The concentrations in the kidney cortex increased from approximately five times those in the liver or the spleen on day 2 to about eight times those on day 20.

Animals↗

PubMed1982

Comparative distribution of laminin, type IV collagen, and fibronectin in the rat glomerulus.

The distribution of laminin, type IV collagen, and fibronectin was investigated in the rat kidney cortex by immunolabeling. It was demonstrated by immunofluorescence on both unfixed cryostat sections and fixed ultracryomicrotome sections, by immunoperoxidase on fixed cryostat sections, and by immunoferritin on isolated glomerular basement membranes (GBM). This multifaceted approach provided complementary and convergent results. Distinct patterns were found for each antigen in the glomerulus and remaining kidney cortex. Laminin was localized predominantly in the GBM, where it was concentrated in the laminae rarae. Staining also occurred to a lesser extent in the mesangial matrix. Type IV collagen was evenly distributed in the lamina densa of the GBM and in the mesangial matrix. Fibronectin was most abundant in the mesangial matrix, but it could also be detected in the peripheral GBM, where it was localized in the laminae rarae. Labeling for fibronectin was particularly prominent at the endothelial-mesangial interface. The findings indicate that the three layers of the GBM differ in their composition: The lamina densa contains type IV collagen and the laminae rarae contain the two attachment proteins, fibronectin and laminin. The mesangial matrix stains for all three antigens, but it is also heterogeneous and can be subdivided into several domains--i.e., the endothelial-mesangial matrix, which is particularly rich in fibronectin, the intermesangial matrix, which contains mainly type IV collagen and fibronectin, and the GBM (where it continues over the mesangial regions), which stains most heavily for laminin.

Albumins↗

PubMed1996

Aldosterone-induced increase in the abundance of Na+ channel subunits.

The highly selective, amilorideblockable Na+ channel is a major target to the natriferic action of the mineralocorticoid aldosterone. This rat epithelial Na+ channel (rENaC) has been recently cloned from colon and is composed of three homologous subunits denoted alpha-, beta-, and gamma-rENaC (C. M. Canessa, L. Schild, G. Buell, B. Thorens, L. Gautschi, J.-D. Horisberger, and B. C. Rossier. Nature Lond. 367: 463-467, 1994). We have tested the effects of corticosteroids on the abundance of mRNA coding for each subunit in kidney cortex and distal colon. Chronic treatment of rats with aldosterone or dexamethasone evoked in kidney cortex a small induction of alpha-rENaC and no change in beta- and gamma-rENaC. In distal colon, however, beta- and gamma-rENaC were strongly induced by either aldosterone or dexamethasone, whereas alpha-rENaC was constitutively expressed. Most of the aldosterone-induced increase in beta- and gamma-rENaC mRNA took place during 3-24 h after plasma aldosterone was elevated. A similar differential induction of rENaC subunits in kidney and colon was also evoked by a Na(+)-free diet. The effects of salt deprivation were reversed by resalinating rats with a half time of < 2 h, suggesting a high turnover rate of at least beta- and gamma-rENaC. The data are consistent with the possibility that induction of channel subunits contributes to the chronic but not the acute response to aldosterone in the colon. Such a mechanism is not likely to play a major role in cortical collecting ducts.

Aldosterone↗