Margaret Gori Mouro

Nitric oxide (NO) is associated with gentamicin (GENTA) nephrotoxicity and the renal function recovery after suspension of GENTA treatment in rats.

GENTA nephrotoxicity is likely to be caused, among other factors, by an increase of vasoconstrictors or a decrease of vasodilators such as NO. Few days after discontinuing GENTA treatment, the renal function is recovered, but if risk factors like advanced age, previous renal dysfunction, simultaneous use of other nephrotoxic drugs or dehydration are present, severe and progressive renal disease occurs. The aim of this study was to evaluate the renal function in rats during GENTA treatment and after its suspension as well as its relationship with NO. Rats were treated with water (vehicle, CTL) or GENTA (100 mg/kg BW) intraperitonially during 10 days; both n=24. Twelve animals of each group were sacrificed after blood and 24 h urine were collected, and their kidneys were removed for histology. In another rats this procedure underwent after 20 or 30 days of GENTA suspension. GENTA treated group developed a marked decrease in renal function, characterized by an increased serum urea and decreased creatinine clearance; NO was increased in the serum and decreased in the urine; all P < 0.01 vs CTL. Acute tubular necrosis was confirmed in GENTA treated group. After GENTA suspension we observed a normalization of urea, creatinine clearance and serum and urinary NO; the histological lesions were also attenuated. We suggest that NO could play a role in GENTA induced nephrotoxicity and recovery. The understanding of this physiopathology could be an useful tool to prevent or blunt the nephrotoxicity progression, mainly when risk factors are present.

Ascorbic acid reduces gentamicin-induced nephrotoxicity in rats through the control of reactive oxygen species

BACKGROUND & AIM Oxidative stress has been implicated in the pathophysiology of many forms of acute renal failure. The aim was examine the effect of vitamin C on oxidative stress and its relationship with nitric oxide on gentamicin-induced nephrotoxicity in rats. METHODS We utilized 32 Wistar rats allocated in four groups of eight animals each: control (CTL), vitamin C (VIT C), gentamicin (GENTA), and GENTA + VIT C; all groups were treated during seven days. RESULTS Serum urea and creatinine, serum and renal tissue malondialdehyde, blood superoxide anion and hydrogen peroxide in GENTA were increased vs CTL and vs VIT C, and decreased in GENTA + VIT C vs GENTA (all P < 0.05). Serum nitric oxide increased in GENTA vs CTL and vs VIT C, and reduced in GENTA + VIT C vs GENTA (P < 0.001). Urinary nitric oxide was reduced in GENTA vs CTL and vs VIT C and increased in GENTA + VIT C vs GENTA (P < 0.001). Severe degeneration of proximal tubules was present in GENTA, but only mild lesions were observed in GENTA + VIT C. CONCLUSION This study suggests that VIT C is a valuable tool to protect against GENTA-induced nephrotoxicity, by reducing reactive oxygen species and increasing the nitric oxide.

Suplementação proteica não aumenta a concentração plasmática de óxido nítrico em homens saudáveis

Nutritional supplements, theoretically able to increase endogenous nitric oxide (NO) production have experienced great popularity among physically active individuals. AIM: scientific evidence available regarding this issue is scarce. Therefore, the purpose of this study was to evaluate the effect of a dietary supplement commercialized as a nitric oxide booster. MATERIALS AND METHODS: twelve sedentary men with no risk factors for cardiovascular diseases were supplemented with placebo or protein in two different occasions. The present study was conducted in a cross double-blind design. In order to assess plasmatic NO concentration, blood samples were obtained before (24hs and immediately before) and after (30 and 60 minutes) consumption of placebo (PLA) or protein supplement (SP). RESULTS: there was no difference in plasmatic nitric oxide concentration between both trails (Post-supplementation 30 min - PLA: 19.3±4.7 µmol.L-1 vs. SP: 18.9±4.4 µmol.L-1 and Post-supplementation 60 min - PLA: 21.3±6.5 µmol.L-1 vs. SP: 20.3±4.9 µmol.L-1). In addition, no difference was detected for arterial blood pressure. CONCLUSION: the dietary supplement analyzed in the present study failed to increase nitric oxide endogenous production.