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Thromboxane A2 (TXA2), leukotrienes (LTs) and free radicals are considered to be possible mediators in the induction of glomerular injury and proteinuria. In this study, we examined the involvement of these three mediators and the protective effect of simultaneous inhibition of all three in puromycin aminonucleoside (PAN) nephrosis in rats. A single intraperitoneal injection of PAN (100 mg/kg) induced massive proteinuria and enhanced production of TXA2 and LTs from arachidonic acid in renal cortical slices and renal glomeruli, and increased malondialdehyde levels in plasma, urine and renal cortex. Oral administration of CV-6504(HCl) (3 to 20 mg/kg/day, for 1 to 2 weeks), a novel treble inhibitor of TXA2 synthetase, 5-lipoxygenase and lipid peroxidation, dose-dependently attenuated PAN-induced proteinuria and the increases in these three mediators. Any single specific inhibitor (CV-4151, a TXA2 synthetase inhibitor; AA-861, a 5-lipoxygenase inhibitor; or CV-3611, a radical scavenger) or a combination of two inhibitors showed no or only a slight antiproteinuric effect, but the combination of all three inhibitors significantly reduced PAN-induced proteinuria. These results suggest that, these three mediators may be involved in the pathogenesis of PAN nephrosis and that CV-6504(HCl), which can simultaneously inhibit all three, may be a useful therapeutic agent for nephrosis.

A quick-freezing and deep-etching method in combination with replica immunoelectron microscopy was applied for examining localization of hyaluronic acid and fibronectin on the upper surface layer of rat mandibular condylar cartilage. Rat temporomandibular joints were dissected with articular disks in order to leave the articular cartilage surface intact. The disks were slightly cut with razor blades for exposing the condylar articular cartilage surface. They were quickly frozen with the isopentane-propane cryogen (-193 degrees C) and prepared for freeze-fracturing and deep-etching replica membranes. They were additionally treated with 5% SDS and 0.5% collagenase to keep some antigens attached on the replica membranes. After such a treatment, a routine immunogold method was applied for clarifying the localization of hyaluronic acid and fibronectin in the upper surface layer. Small immunogold particles for hyaluronic acid were mainly localized around upper filamentous networks covered with amorphous materials, but large immunogold ones for fibronectin were localized on deep thicker fibrils. We have revealed the native architecture of the upper surface layer of mandibular condylar cartilage on the replica membranes and also three-dimensional localization of hyaluronic acid and fibronectin by the immunogold method.