Selective inhibition of inducible nitric oxide synthase enhances intraglomerular coagulation in chronic anti-Thy 1 nephritis

Abstract

Selective inhibition of iNOS aggravated albuminuria in chronic aThy 1-GN in LEW/Maa rats. Induction of iNOS during the inflammatory phase of this model may be a partially protective mechanism by interfering with intraglomerular coagulation processes.

Inducible Nitric Oxide Synthase–Derived Nitric Oxide Promotes Glomerular Angiogenesis via Upregulation of Vascular Endothelial Growth Factor Receptors

“…In confirmation of our previous findings (21), treatment of nephritic rats with L-NIL led to a significant increase of albuminuria, whereas basal albuminuria in nonnephritic controls remained unchanged by L-NIL treatment (Table 3). However, in contrast to our previous study (21), increased albuminuria in L-NIL-treated nephritic rats was not associated with an aggravation of mesangiolysis, glomerular microaneurysm formation, or evidence of increased intraglomerular thromboses (data not shown). Because iNOS inhibition was started before the induction of anti-Thy 1.1 nephritis, one potential concern is that this treatment modified the glomerular binding of ER4 anti-Thy 1.1 antibody and thereby affected the induction phase of the disease.…”

“…It is 23-fold more selective for iNOS versus nNOS and 49-fold more selective for iNOS versus eNOS. It has no other known pharmacologic actions apart from competition with L-arginine for cellular uptake, and it has been used widely to probe the effects of iNOS inhibition (21)(22)(23)(24). The in vivo dose of L-NIL (60 mg/kg) was chosen to resemble directly a previous study in the same model for reasons of comparability (21).…”

“…Selective iNOS inhibition in 10 nephritic and four healthy control rats was achieved by administration of 60 mg/kg body wt L-NIL per day in the drinking water. The dosage was chosen on the basis of previous experience (21) and assuming that fluid intake compares well to urine volumes. Rats were housed in metabolic cages to measure urine output (range, 14 to 20 ml/d), and concentrations of L-NIL in the drinking water were prepared accordingly.…”

“…Kidneys were perfused with 25 ml of ice-cold PBS and removed, and a renal cortical section per rat was obtained for light microscopy. The remaining cortical tissue of each animal was used to generate a preparation of glomeruli by differential sieving (14,21). All glomerular isolates were checked microscopically and exhibited a purity of Ͼ95%.…”

“…Urinary albumin levels were determined on a 96-well ELISA plate, using a peroxidase-conjugated anti-rat albumin antibody (ICN-Biomedical, Eschwege, Germany), as described (21). All measurements were performed in duplicate.…”