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It was examined whether superoxide dismutase (SOD) had protective effects in puromycin aminonucleoside nephrosis (PAN). Nephrotic rats were induced by a single intraperitoneal injection of puromycin aminonucleoside (PA, 60 mg/kg). Subcutaneous administration of SOD (30 mg/kg) was started the day before PA injection and continued every 24 hours. Animals were sacrificed 10 days later to assess the morphology and glomerular basement membrane anionic charge sites (CSs). GBM CSs were stained in vitro with polyethyleneimine (PEI) and studied by electron microscopic examination. The SOD-injected group had a significant reduction of urinary protein excretion compared to the PA-treated group. Light microscopy revealed that vast majority of glomeruli in PA-treated group had segmental mesangial expansion and epithelial cell adhesions of the glomerular tuft to Bowman's capsule. Contrasted to these changes in the PA group, glomeruli from SOD-treated group showed less severe morphologic changes. On electron microscopy, the PA-treated rats exhibited marked glomerular epithelial loss of foot processes, epithelial attenuation, cytoplasmic vacuolization and protein reabsorption droplets. The SOD-treated animals demonstrated a lesser degree of epithelial loss of foot processes with a few protein reabsorption droplets. There was also a significant decrease in GBM lamina rara externa CSc stained with PEI in PAN compared to the control. The SOD-treated rats had a significant increase in GBM CSs compared to those of the PAN rats. SOD has protective effects in urinary protein excretion, the morphology and GBM CSc in PAN, which indicate indirect evidence that superoxide and/or its metabolites are responsible for glomerular injury.

In order to demonstrate the early effect of sodium iodate (NaIO3) on retinal pigment epithelium (RPE), Bruch's membrane and choriocapillaries, we examined the alteration of their anionic sites using a cationic probe, polyethyleneimine (PEI). We injected 10 microliters of 3% NaIO3 solution into the vitreous of pigmented rabbits and after thirty minutes or one hour, administered 0.5% PEI intravenously. In the eyes injected with intravitreously saline solution or without injection, PEI-positive particles (diameter 15-20 nm) were located in a row on both sides of the basement membrane of the RPE and choriocapillaries and periodically at the collagen fiber of inner and outer collagenous zone of Bruch's membrane. However no particle was observed on the cell membrane of the basal infolding of the RPE. Thirty minutes after injection of NaIO3, PEI particle positive sites were reduced at the basement membrane of the RPE. One hour after injection they reduced in number but remained at the basement membrane of choriocapillaris and collagens in Bruch's membrane. We showed the early effect of NaIO3 to the RPE by examining the alterations of the anionic sites.

The methods of basolateral membrane isolation from rat kidney and 3H-AVP receptor assay using this basolateral membrane preparation were established. Then, the effects of analogues and drugs on AVP-receptor binding were studied. Specific 3H-AVP binding was inhibited by LVP, dDAVP and oxytocin in that order. Among the various agonistic or antagonistic drugs to AVP (fluoride, cyclophosphamide, mechlorethamine, chlorpropamide), only chlorpropamide inhibited 3H-AVP binding to the membrane. The Kd value calculated by Scatchard analysis was 1.30 +/- 0.28 nM (n = 4, M +/- SD), and it was increased to 2.69 +/- 0.32 nM (n = 5, M +/- SD) by adding 1 mM of chlorpropamide, while Bmax was unchanged. Our data show that 1 mM chlorpropamide decreases receptor affinity for AVP, and alters AVP-receptor binding in a competitive manner.