Superoxide–Mediated Glomerulopathy in the Endotoxin–Treated Pregnant Rat

Abstract

In the present study the role of superoxide in the glomerular damage in the low-dose endotoxin-infused pregnant rats was investigated. On day 14 of pregnancy, 12 rats were infused for 1 h with 1.0 microgram/kg bw endotoxin via a permanent jugular vein cannula. Of these rats, 6 were treated with SOD both prior to endotoxin infusion (7,000 U/kg) and 30 min (7,000 U/kg) and 4 h (14,000 U/kg) after the start of the infusion (SOD rats). The other 6 rats received no SOD treatment (endotoxin rats). Control pregnant rats were infused for 1 h with saline (saline rats; n = 6). Urinary albumin was measured on days 15 and 19 of pregnancy. On day 21, rats were sacrificed and kidney specimens were snap-frozen. Cryostat kidney sections were stained for fibrinogen, ecto-ATP diphosphohydrolase (e-ATPase) activity, polymorphonuclear cells, monocytes and various adhesion molecules on the endothelium and the leukocytes. SOD treatment appeared to significantly prevent the increased urinary albumin excretion and the decrease of glomerular e-ATPase activity which were observed in endotoxin-treated rats. This effect of SOD treatment after endotoxin infusion was associated with a significant inhibition of glomerular monocyte influx and a significant inhibition of adhesion molecule expression (glomerular ICAM-1 and VCAM-1 and leukocyte LFA-1 and VLA-4). The present data suggest that in the endotoxin-infused pregnant rat, production of superoxide in the first few hours after the infusion plays a role in the induction of glomerular damage, leading to albuminuria and diminished e-ATPase expression during the following days.