Aim: 

Females suffer a less severe ischemic acute renal failure (I/R) than males, apparently due to lower levels of oxidative stress. Because I/R derangement is associated with renal outer medullary endothelial dysfunction, the present study evaluated the gender differences in OM changes in nitric oxide ([NO]) and peroxynitrite levels (ONOO) during 45 min of ischemia and 60 min of reperfusion in anesthetized SD rats.

Methods: 

[NO], ONOO, dimeric, phosphorilated NO synthases expression (PeNOS and PnNOS), 3-nitrotyrosine levels, reduced sulphydryl groups (-SH) and glomerular filtration (GFR) were determined.

Results: 

PeNOS and PnNOS and basal [NO] (466.644.5 and 462.547.3 nmol/L) were similar in non-ischemic kidneys of both groups. Ischemia produced a similar increase in PeNOS and PnNOS isoforms expression; however, [NO] was higher in females (6406.0742.5 nmol/L) than males (4058.2272.3 nmol/L). ONOO was lower in females (10.070.8 nA) than males (14.52.7 nA) during ischemia. NO and peroxynitrite dropped to near basal levels during reperfusion in both groups, although peroxynitrite remained significantly higher in antioxidant untreated males.–SH content fall and nitrotyrosine levels were lower in females (-43.33.3% and 28.73.7 nmol/mg protein) than males

(-68.43.9% and 48.73.7 nmol/mg proteín). Twenty-four hours after ischemia, GFR was better preserved in females than males (689.7135.0 vs. 221.452.5 mL/min/g kwt). Antioxidant N-acetyl-Lcysteine or peroxynitrite scavenger ebselen treatment of males abolished the gender differences in peroxynitrite, nitrotyrosine and GFR.

Conclusion: 

The better renal function preservation in females during ischemia-reperfusion is associated with higher [NO] and lower ONOO during ischemia, indicating a greater oxidative and nitrosative stress in males.