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At least 523 records · Page 29Linked to original sources
PubMed1986

Electron microscopic cytochemical localization of alpha-hydroxyacid oxidase in rat kidney cortex. Heterogeneous staining of peroxisomes.

The substrate specificity of alpha-hydroxyacid oxidase in the rat kidney has been investigated cytochemically by the cerium technique and biochemically with a luminometric assay applied to isolated renal peroxisomes. Rat kidneys were fixed by perfusion via the abdominal aorta with a low concentration (0.25%) of glutaraldehyde. Vibratome sections were incubated for 60 min at 37 degrees C in a medium containing 3 mM CeCl3, 100 mM NaN3 and 5 mM of an alpha-hydroxyacid in 0.1 M Pipes or 0.1 M Tris-maleate buffer both adjusted to pH 7.8. Ten aliphatic alpha-hydroxyacids with chain lengths between 2 and 8 carbon atoms and two aromatic substrates were tested. The alpha-hydroxyacid oxidase in the kidney exhibited a markedly different substrate specificity than the corresponding enzyme in the liver. Thus glycolate gave a negative reaction while two aromatic substrates, mandelic acid and phenyllactic acid, stained prominently. With aliphatic substrates a stronger reaction was obtained in Pipes than in the Tris-maleate buffered incubation media. The best reaction in the kidney was obtained with hydroxybutyric acid. These cytochemical findings were confirmed by the luminometric determination of the oxidase activity in isolated purified peroxisome fractions. By electron microscopy the electron dense reaction product of cerium perhydroxide was found in the matrix of peroxisomes in the proximal tubules. The intensity of reaction varied markedly in neighbouring epithelial cells but also in different peroxisomes within the same cell. Thus heavily stained particles were seen next to lightly reacted ones. These observations establish the substrate specificity of alpha-hydroxyacid oxidase in the rat kidney and demonstrate the marked heterogeneity in the staining of renal peroxisomes for this enzyme.

Alcohol Oxidoreductases↗
PubMed2000

Age-dependent expression of fibrosis-related genes and collagen deposition in rat kidney cortex.

Because progressive fibrosis is a histological hallmark of the aging kidney, we sought to characterize the course of some fibrosis-related genes [pro-alpha2(I)collagen (COL-I), pro-alpha1(III)collagen (COL-III), and transforming growth factors beta1 and beta3 (TGF-beta1 and TGF-beta3)] of interstitial collagen accumulation [COL-I and COL-III proteins, hydroxyproline (PRO-OH), histology] and its degradation (matrix metalloproteinase MMP-1 and -2) during maturation and early aging in rats. During the lifespan considered we observed no changes in the mRNA, except that COL-I mRNA tended to be up-regulated from 2 to 19 months of age. However, progressive fibrosis was histologically detectable, with COL-I accumulation (p < .05 and p < .01 in 12-month- and 19-month-old rats vs the youngest), and confirmed by the PRO-OH tissue levels (p = .0001); COL-III seemed to be less involved. The MMP-1 protein level decreased significantly in the cortex of 12-month- and 19-month-old rats (p < .05), whereas MMP-2 protein level and activity remained essentially unchanged. These results show that, during aging of the kidney, (i) renal cortex fibrosis is explained by COL-I accumulation as a consequence of an altered balance between its synthesis and degradation, and (ii) the expression of the pleiotropic factor TGF-beta in the renal cortex is not modified.

Age Factors↗
PubMed1984

The effect of racemomycin-D, a nephrotoxic antibiotic, on cellular metabolism of rat kidney cortex in vitro.

In vitro effects of racemomycin-D on cellular metabolism were examined in rat kidney. Racemomycin-D decreased the concentration gradient of Na+ and K+ across the cell membranes, but failed to influence water content and ATP concentration of kidney cortical slices. The antibiotic inhibited microsomal (Na+ + K+)-ATPase. Preincubation of the microsomes with racemomycin-D enhanced the inhibition about 1.8-fold. Succinoxidase activity of mitochondria remained unaltered in the presence of racemomycin-D, but the antibiotic potently decreased ATP-dependent Ca2+ and Mg2+ uptakes by mitochondria. These results suggest that racemomycin-D probably disorders intracellular homeostasis of Na+, K+ and Ca2+.

Adenosine Triphosphate↗
PubMed1991

Effects of Fe2+, Fe3+ and desferrioxamine on paraquat accumulation by rabbit kidney cortex slices.

Effects of Fe2+, Fe3+ and desferrioxamine (DFO) on the accumulation of paraquat (PQ) into rabbit kidney cortical slices were studied. Fe3+ showed dose-dependent inhibition of PQ accumulation. Fe2+ had a more powerful stimulatory effect on the lipid peroxidation of cortical slices than Fe3+, but it did not reduce PQ accumulation. The addition of DFO made the inhibitory effect of Fe3+ on PQ accumulation more pronounced. These results suggest that Fe3+ is able to inhibit the accumulation of PQ independent of its peroxidative action, and that Fe(3+)-desferrioxamine (ferrioxamine) may serve as an antidote for the toxicity of PQ.

Animals↗
PubMed1989

Inhibition of paraquat accumulation in rabbit kidney cortex slices by ascorbic acid.

Effects of ascorbic acid and Fe2+ on the accumulation of paraquat into rabbit kidney cortical slices were studied. Ascorbic acid showed dose-dependent inhibition of paraquat accumulation. Fe2+ had a more powerful stimulatory effect on the lipid peroxidation of cortical slices than ascorbic acid, but it did not reduce paraquat accumulation. These results suggest that ascorbic acid is able to inhibit the accumulation of paraquat independent of its peroxidative action, and that ascorbic acid may serve as an antidote for the toxicity of paraquat.

Animals↗
PubMed1992

Isolation of a cDNA for rat CHIP28 water channel: high mRNA expression in kidney cortex and inner medulla.

The cDNA coding for the rat CHIP28 water channel was isolated from a kidney library. At the amino acid level, rat CHIP28 is 93% identical to the recently published human protein (1). Expression of rat CHIP28 mRNA was highest in the renal inner medulla, unchanged during antidiuresis and twice the level expressed in outer cortex, with lower expression levels also apparent in parotid gland, urinary bladder and prostate. The evidence suggests that CHIP28 water channels in the ADH-sensitive collecting tubules are identical to those of the ADH-insensitive proximal convoluted tubules and possibly other tissues specialised in fluid transport.

Amino Acid Sequence↗