Effects of Chronic Administration of Different Doses of Nitrate on Renal Function in Female Rats

Introduction: As a nitric oxide (NO) donor, nitrate administration improves renal function in male animals. This study aims to determine the effects of chronic administration of different doses of nitrate on kidney function in normal adult female rats by measuring serum urea and creatinine and assessing the estimated glomerular filtration rate (eGFR). Materials and Method: Two-month old female Wistar rats were divided into six groups (n=10/group): the control group received tap water, and five nitrate-treated groups received water containing 50, 100, 150, 250, and 500 mg/L sodium nitrate in their drinking water for six months. At the end of the study, body weight, serum urea, and serum creatinine were measured, and eGFR was calculated. Results: Serum urea levels decreased by 16.9% (P=0.037) at dose 100 mg/L and increased by 15% (P=0.064) and 24.7% (P=0.003) at doses 250 and 500 mg/L, respectively, after nitrate administration. Serum creatinine levels decreased only at dose 100 mg/L by 16.3% (P=0.002) after nitrate administration. Moreover, eGFR increased at dose 100 mg/L (11.5%, P=0.046), decreased at doses 250 (13.8%, P=0.018) and 500 (16.9%, P=0.004) mg/L, and remained constant at doses 50 and 150 mg/L after nitrate administration. Conclusion: Chronic nitrate administration exerted multiphasic effects on renal function in female rats; i.e., the low dose had no effect, the intermediate dose had a protective effect, and the high dose had detrimental effects on renal function.