ISSN:1420-4096    

DOI:10.1159/000173176

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The subcellular distribution of dipeptidyl peptidase II (DPP II) in the rat kidney cortex, as determined by subfractionation of the mitochondrial/lysosomal fraction by rate sedimentation, indicated that this enzyme is mainly associated with the large, fast sedimenting lysosomes (protein droplets). The small lysosomes, on the other hand, displayed considerable size heterogeneity as indicated by the broad distribution of DPP II; cathepsin B, and a tripeptidyl peptidase active on Gly-Pro-Met-2-naphthylamide at pH 4 (TPP 4). Cathepsin D and N-acetyl-β-D-glucosaminidase were limited primarily to the slower-sedimenting, small lysosomes. Equilibrium banding in sucrose gradients of the two main DPP II-containing lysosomal populations showed that the large lysosomes banded at a density of 1.235-1.24 g/ml while small lysosomes banded at three densities: 1.11-1.15 g/ml (lysosomal fragments), 1.20 g/ml (light lysosomes), and 1.235 g/ml (dense lysosomes). Identical distribution pattern were obtained for DPP II using either Lys-Ala-7-(4-methyl)coumarylamide or Gly-Pro-2-naphthylamide as the substrate at pH 5.5 and 5.0, respectively. Notably, DPP II and TPP 4, and cathepsin B as well, gave banding densities and distributions that were consistent with a lysosomal localization. Since triplets of the Gly-Pro-X-type released by the TPP 4 are ideal substrates for DPP II, the integrated action of tripeptidyl and dipeptidyl peptidases could make a novel contribution to the renal depolymer-ization and reabsorption of polypeptides, in particular the proline-rich, collagen-derived sequences that possess repeating-triplet primary structures

ISSN:1420-4096    

DOI:10.1159/000173177

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

Pepsinogen A (PGA) and pepsinogen C (PGC) are low-molecular-weight proteins synthesized by the gastric mucosa. Data in man suggest that both pepsinogens are almost freely filtered through the glomerular basement membrane despite a molecular weight of about 43,000 dalton and a strongly negative charge. This promoted us to investigate the glomerular sieving of PGA and PGC in the isolated rat kidney model by measuring their fractional excretions before and after inhibition of tubular function with sodium iodoacetate. During the control episode fractional excretion of PGA was 40 ± 0.04% and of PGC 42 ± 0.04% (mean ± SEM from 9 experiments). After complete inhibition of tubular function a large increase in fractional excretion was found for both pepsinogens: 87 ± 0.04% for PGA and 95 ± 0.09% for PGC. It is concluded that tubular secretion does not contribute to the high fractional excretion of pepsinogens and that both PGA and PGC are almost freely filtered through the glomerular basement memb

ISSN:1420-4096    

DOI:10.1159/000173178

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

A method was developed to monitor the occurrence of lipid peroxidation (LPO) during ischemia and Na-maleate-induced acute renal failure (ARF) on male rats in vivo by measuring malondialdehyde (MDA) levels in arterial and renal venous blood and in urine. No signs of LPO could be detected under control conditions. In ischemic ARF produced by 45 min of renal artery clamping a steep increase of MDA was found in the renal venous effluent immediately after starting reperfusion. This effect was nearly abolished after 5 min of blood reflow while glomerular filtration remained at 5% of control value during a 90-min postischemic observation period. Intoxication with Na-maleate leads to enhanced LPO in combination with an impaired renal function 2 h after administration. These findings would well explain cellular damage and some aspects of renal dysfunction associated with the initation phase of ARF.

ISSN:1420-4096    

DOI:10.1159/000173179

出版商:S. Karger AG    

年代:1989

数据来源: Karger

摘要:

The morphologic changes in sodium-maleate-induced acute renal injury in the rat were quantified by a stereologic analysis. The major changes were confined to an increase in endocytic vacuoles and a decrease in mitochondrial inner membrane surface area. These results were found to be linked to significantly increased urinary activities of the cytosolic enzymes fructose-1 6-bisphosphatase (FBP) and lactate dehydrogenase, the lysosomal enzyme N-acetyl-β-glucosaminidase (NAG) and the NAD-dependent mitochondrial isocitrate dehydrogenase (ICDH). The highest increase was found for NAG, followed by FBP and ICDH

ISSN:1420-4096    

DOI:10.1159/000173180

出版商:S. Karger AG    

年代:1989

数据来源: Karger