LTB4 in nephrotoxic serum nephritis in rats

Abstract

We studied leukotriene B4 (LTB4) synthesis in isolated glomeruli of rats with nephrotoxic serum nephritis. This nephritis was induced in male Sprague Dawley rats by injecting one proteinuric dose of nephrotoxic serum (rabbit anti-rat-GBM serum) after prior immunization of the rats with rabbit IgG. Histological and analytical examinations were performed in kidneys perfused until free of blood 6, 12, 24, 48 and 72 hours after induction of the disease. To investigate LTB4 production, glomeruli were isolated and incubated for one hour in the presence of Ca++-ionophore A23187. The supernatants were analyzed for LTB4. The peak comigrating on reverse-phase high performance liquid chromatography (RP-HPLC) with reference LTB4 was isolated. The ethyl ester trimethylsilyl ether derivative of this peak was analyzed by gaschromatography-mass spectrometry (GC/MS). Identical spectra of the glomerular samples and of reference LTB4 in the positive and in the negative ion chemical ionization mode provided unequivocal evidence that the substance released from the nephritic glomeruli was indeed LTB4. Six hours after injection of nephrotoxic serum, glomerular LTB4 release was highest with 5.52 +/- 0.50, then declining to 2.20 +/- 0.10 ng/mg glomerular protein at 12 hours. At 24, 48 and 72 hours no statistically significant difference from control animals was found. No metabolism of LTB4 to 20-hydroxy- or 20-carboxy-LTB4 was detected during the incubation period. Albuminuria developed during the first 24 hours after nephrotoxic serum challenge and rose steadily throughout the observation period up to 277 +/- 25 mg/24 hr after 72 hours.(ABSTRACT TRUNCATED AT 250 WORDS)