Glomerular barrier function for serum proteins in experimental heart failure.
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Biomedical subjects
W Gwinner
Publications and source records attributed to W Gwinner.
Adriamycin affects glomerular renal function: evidence for the involvement of oxygen radicals.
The early nephrotoxic effect of the antitumor drug adriamycin (ADR) is suggested to be related to the generation of oxygen free radicals. Therefore the O2-dependence and the influence of free radical scavengers were studied in the model of the isolated perfused single glomerulus of Myxine glutinosa and by histochemical demonstration of the glomerular ATP-ase. In Myxine, the glomerular ATP-ase activity was decreased after injection of ADR (5 mg/kg, i.v.). Both ADR-treated Myxine and controls were exposed for 48 h to an artificial atmosphere of 20% O2/80% N2 or 80% O2/20% N2, respectively. After 10 days a significant decrease of the hydraulic conductivity (k) was measured in the experimental group exposed to 80% O2 (k-values expressed as nl/s.mm Hg.mm2: controls (7): 0.059 +/- 0.017; ADR (7): 0.033 +/- 0.026). The reduction of k following the administration of ADR (20 mg/kg) could be prevented by the sulphydryl donor N-acetylcysteine (NAC). The sieving coefficient for albumin (phi) was significantly increased in ADR-treated animals, showing no O2-dependence (phi x 10(-2): controls (7) 1.3 +/- 0.2; ADR 20% O2 (8): 8.1 +/- 9.6; ADR 80% O2 (7): 6.9 +/- 6.7). phi was not affected by NAC. The lipid peroxide levels in liver, kidney and heart of Myxine increased after the administration of ADR, peaking by day 2 to 5. The circulation disorders of ADR-treated Myxine were not due to an accumulation of the drug in the heart, but rather to a lack of the intracellular antioxidant glutathione. It is concluded that the early nephrotoxic effect of ADR, as reflected by a decreased glomerular ATP-ase activity, is mediated by free radical formation. Oxidative stress on membrane compounds seems to reduce the water permeability of the glomerular barrier, while the ADR-induced sieving defect may be due to oxygen independent pathological mechanisms.
Adenosine Triphosphatases↗
Metabolic rates of 4-hydroxynonenal in tubular and mesangial cells of the kidney.
The degradation of the lipid peroxidation product 4-hydroxynonenal (HNE) in primary cultures of kidney tubular and mesangial cells was determined. Using various initial concentrations of the aldehyde a decline of cellular viability was found. Mesangial cells were more susceptible to the toxic effects of HNE. In consumption studies of HNE the decline of the exogenously added aldehyde was comparable in both cell types after addition of 10 and 1 micromol HNE/l. After addition of 100 micromol/l aldehyde a drastically lower HNE degrading capacity was found in mesangial cells as compared to tubular cells. The loss in the HNE degrading capacity was accompanied by an increased formation of HNE-protein aggregates as demonstrated by immunoblots. Therefore, we concluded that the low ability of mesangial cells to degrade HNE may be a factor of the toxicity of free radicals on the kidney.
Aldehydes↗
The Munich Wistar Frömter rat: proteinuria and blood pressure in correlation to the number of superficial glomeruli.
Rats with a high number of superficial nephrons (MWF/Ztm) also show an elevated urinary protein excretion and a high systolic blood pressure. To investigate a possible correlation between the number of superficial glomeruli and these physiological changes, MWF/Ztm rats were crossed and backcrossed to Wistar cryptorchic (WC/Ztm) animals with no superficial nephrons in order to produce genotypes with differing numbers of superficial glomeruli. In the parental strains, the F1 hybrids and the 8 possible backcrosses, the number of superficial glomeruli, the distance of the 10 most superficial glomeruli to the renal surface, and the diameter of Bowman's capsules were determined by morphometric analysis. The excretion of total protein, in detail low molecular weight proteins, albumin, and high molecular weight proteins were measured quantitatively in 5 males of each genotype. Systolic blood pressure was determined by a tail-cuff method in conscious rats. Means of each variate of the 12 available genotypes were linearly correlated and demonstrate a close correlation between the amount of superficial nephrons and the observed physiological changes, i.e. the more superficial the glomeruli the higher the urinary protein excretion, especially albumin, and the higher the systolic blood pressure.
Albuminuria↗
Heat-aggregated IgG and interleukin-1-beta stimulate manganese superoxide dismutase in mesangial cells.
The response of the glomerular mesangial cell to reactive oxygen species (ROS) has been implicated in the pathogenesis of several forms of inflammatory renal disease. As a model of glomerular inflammation, we studied the effects of heat-aggregated immunoglobulin G (HAG), an experimental immune complex, and interleukin-1 (IL-1) on the expression of the antioxidant enzyme, manganese superoxide dismutase (MnSOD), in primary cultures of rat mesangial cells. Following exposure to either HAG or IL-1 beta, increased steady-state MnSOD mRNA levels were observed and an additive effect was seen following co-treatment with HAG and IL-1 beta. No change was observed in steady-state levels of copper/zinc superoxide dismutase mRNA with HAG or IL-1 beta exposure. RNA protein synthesis inhibitor experiments demonstrated that the HAG- and IL-1 beta-mediated increase in MnSOD mRNA was dependent on new transcription, but was independent of de novo protein synthesis. Our data on the induction of the MnSOD gene by immune complexes and IL-1 beta could indicate an important role for MnSOD in the cellular defense against ROS toxicity in glomerular inflammation.
Animals↗