Renal metabolism and urinary excretion of platelet-activating factor in the rat
- Mario Negri Institute for Pharmacological Research, Bergamo (Italy)
The origin of platelet-activating factor (PAF) in the urine remains ill defined. The present study documents that (3H)PAF (3.5 mu Ci) injected into the renal artery of isolated control rat kidney preparations perfused at constant pressure with a cell-free medium containing 1% bovine serum albumin (BSA) was excreted in negligible amounts (0.034%) in the urine, whereas 6% was retained by the kidney. When kidneys were perfused with a BSA-free medium, 0.029 and 71% of the total radioactivity added to the perfusate was recovered in the urine and in the renal tissue, respectively. (3H)PAF urine excretion in proteinuric kidneys from adriamycin-treated rats was still negligible (0.015%). Analysis of the renal tissue-retained radioactivity in control and proteinuric kidneys perfused with 1% BSA indicated metabolism into long chain acyl-sn-glycero-3-phosphorylcholine species, lyso-PAF, glycerols, and intact PAF. Thin layer chromatography analysis of (3H)glycerol fraction in these renal extracts showed two major components comigrating with 1-O-alkylglycerol and 1-O-alkyl-2-fatty acylglycerol. Isolated proximal tubules, but not glomeruli from nephrotic rats exposed to increasing concentrations of BSA (0-4%), had a higher PAF uptake than control tubules for BSA concentrations ranging from 0 to 0.1%. Our findings in the isolated perfused kidneys indicate that, in normal conditions, circulating PAF is excreted in the urine in negligible amounts and that the altered glomerular permeability to proteins does not affect this excretion rate. Moreover, analysis of renal tissue radioactivity documented that the renal metabolism of PAF is comparable in control and nephrotic kidneys.
- OSTI ID:
- 6170743
- Journal Information:
- Journal of Biological Chemistry; (USA), Journal Name: Journal of Biological Chemistry; (USA) Vol. 265:32; ISSN JBCHA; ISSN 0021-9258
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ALBUMINS
ALCOHOLS
ANIMALS
BIOLOGICAL MATERIALS
BIOLOGICAL WASTES
BLOOD COAGULATION FACTORS
BODY
BODY FLUIDS
CHROMATOGRAPHY
CLEARANCE
COAGULANTS
DISEASES
DRUGS
EXCRETION
GLYCEROL
HEMATOLOGIC AGENTS
HYDROGEN COMPOUNDS
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
KIDNEYS
MAMMALS
MATERIALS
METABOLISM
ORGANIC COMPOUNDS
ORGANS
PERFUSED ORGANS
PROTEINS
RATS
RENAL CLEARANCE
RODENTS
SEPARATION PROCESSES
THIN-LAYER CHROMATOGRAPHY
TRACER TECHNIQUES
TRITIUM COMPOUNDS
URINE
UROGENITAL SYSTEM DISEASES
VERTEBRATES
WASTES