Association of nitric oxide production and apoptosis in a model of experimental nephropathy

Background. In recent studies increased amounts of nitric oxide (NO) and ap optosis have been implicated in various pathological conditions in the kidn ey. We have studied the role of NO and its association with apoptosis in an experimental model of nephrotic syndrome induced by a single injection of adriamycin (ADR). Methods. The alteration in the NO pathway was assessed by measuring nitrite levels in serum/urine and by evaluating the changes in vascular reactivity of the isolated perfused rat kidney (IPRK) system. Rats were stratified in to control groups and ADR-induced nephropathy groups. These two groups were then divided into: group 1, animals receiving saline; and group 2, animals receiving aminoguanidine (AG) which is a specific inhibitor of inducible-N O synthase. On day 21, rats were sacrificed after obtaining material for bi ochemical analysis. Results. Histopathological examination of the kidneys of rats treated with ADR revealed focal areas of mesangial proliferation and mild tubulointersti tial inflammation. They also had significantly higher levels of proteinuria compared with control and treatment groups (P < 0.05). Urine nitrite level s were significantly increased in the ADR-nephropathy group (P < 0.05). In the IPRK phenylephrine and acetylcholine related responses were significant ly impaired in the ADR-nephropathy group. Apoptosis was not detected in con trols. However, in the ADR-nephropathy group, numerous apoptotic cells were identified in the tubulointerstitial areas. Double staining revealed numer ous interstitial apoptotic cells to stain for ED1, a marker for monocytes/m acrophages. Treatment with AG prevented the impairment of renal vascular be d responses and reduced both urine nitrite levels and apoptosis to control levels. Conclusion. We suggest that interactions between NO and apoptosis are impor tant in the pathogenesis of the ADR-induced nephrosis.