Increased expression of nitric oxide synthase coincides with reversal of renovascular hypertension

The present study was aimed at investigating whether there are changes in the expression of nitric oxide synthase (NOS) in relation with the unclipping-induced fall of blood pressure in two-kidney, one clip (2K1C) hypertension. Male Sprague-Dawley rats were made 2K1C hypertensive by clipping the left renal artery for four weeks. Sham-clipped rats served as control. The expression of endothelial constitutive (ec) NOS proteins and tissue levels of NO metabolites were determined in the kidney. Systolic blood pressure was significantly increased in clipped rats compared with that in the control. The development of hypertension was associated with decreases in the expression of ecNOS proteins and tissue levels of NO metabolites in the clipped kidney. The blood pressure at twenty-four hours after removal of the renal arterial clip fell to the control level. Accordingly, in the unclipped kidney, the expression of ecNOS proteins and tissue contents of NO metabolites were increased to the control level. The contralateral kidney was not affected by the development or reversal of hypertension. It is suggested that an enhanced expression of ecNOS in the unclipped kidney is an important component in the reversal of renovascular hypertension.

Effect of vitamin C on plasma total antioxidant status(TAS) in patients with paraquat intoxication / 대한내과학회지

BACKGROUND: This study was undertaken to evaluate the effect of plasma concentration of vitamin C is on the plasma total antioxidant status(TAS) in patients with paraquat intoxication. METHODS: As a preliminary research for this study, we measured plasma vitamin C levels, uric acid, TAS, and bilirubin from 100 healthy Koreans aged between 25-55 years. Various concentrations of vitamin C were constructed in vitro with normal pooled plasma between 1mg/dl and 100 mg/dL and TAS was measured. Both vitamin C concentrations and TAS were measured from the blood samples, taken at 0.5, 1, 2, 3, 5, 7, 9 hours after a bolus injection of vitamin C(50 mg/kg) from 7 volunteers who had been recruited from medical students at our hospital. Various amounts of vitamin C were given to 10 patients with paraquat intoxication for 5 consecutive days in the morning : first day ; 100 mg single dose, second day; 500 mg single dose, third day ; 1,000 mg single dose, fourth day : 3,000 mg single dose, and fifth day ; 3,000 mg three times every 8 hours. RESULTS: The mean value of TAS and vitamin C measured in 100 healthy Korean adults was 2.22 +/-0.16 mmol/L and 0.48+/-0.10 mg/dL. Age and sex do not influence these levels(p> 0.05, data are not presented). A direct correlation was observed between TAS and vitamin C concentrations of 1 mg/dL and 100 mg/dL both in vivo and vitro. As the vitamin C concentration was increased gradually 5 consecutive days, the TAS values increased in the same way as follows : first day(vitamin C 100 mg) 2.26+/-0.98 mmol/L, second day(vitamin C 500 mg) 2.76+/-0.78 mmol/L, third day(vitamin C 1.000 mg) 2.81+/-0.68 mmol/L, fourth day(vitamin C 3.000 mg) 3.18 mmol/L. On the fifth day when 3.000 mg of vitamin C was given by bolus intravenous injection 3 times(every 8 hours for a day), the TAS values measured one hour after the injection was 3.58+/-0.37 mmol/L. CONCLUSION: When vitamin C is used as a free radical scavenger, the loading dose and maintenance dose should be around 2278 mg intravenous bolus and 146 mg/hour. High doses of vitamin C are effective and safe for patients with acute paraquat intoxication.