Taurine prevents hypertension and increases exercise capacity in rats with fructose-induced hypertension.

BACKGROUND: Fructose-induced hypertension was used to test the hypothesis that taurine supplementation and/or exercise can prevent hypertension and increase exercise capacity. METHODS: Five groups of 15 Sprague-Dawley rats were allocated and designated as control, high fructose-fed (fructose), high fructose-fed plus exercise (FE), high fructose-fed plus 2% taurine supplement (FT) and high fructose-fed plus 2% taurine supplement and exercise (FET) groups. Noninvasive systolic blood pressure (SBP) was recorded weekly and invasive arterial blood pressure (ABP) was recorded at the end of the 4-week trial. Three consecutive swimming tests were performed in the selected rats from each group and the plasma biomarkers were measured in the remaining rats. RESULTS: Noninvasive SBP differed significantly (P < 0.001) from week 3, both noninvasive and invasive ABP increased significantly (P < 0.001), and exercise capacity significantly decreased (P < 0.001) in the fructose group compared with the control group. The individual effects of swimming and taurine supplementation were incapable of preventing the development of hypertension and SBP significantly (P < 0.001) increased in the FE and FT groups; exercise capacity in those groups remained similar to control. The combined effects of exercise and taurine alleviated hypertension and significantly increased exercise capacity in the FET group. Insulin resistance increased significantly and plasma nitric oxide (NO) decreased significantly in the F, FE, and FT groups. Both parameters remained similar to control values in the FET group with an increasing antioxidant activity. CONCLUSION: Taurine supplementation in combination with exercise prevents hypertension and increases exercise capacity by possibly antioxidation and maintaining NO concentrations.

Myocardial calcification and hypertension following chronic renal failure and ameliorative effects of furosemide and captopril.

OBJECTIVES: The aim of this study was to prevent metastatic myocardial calcification and hypertension following chronic renal failure (CRF). METHODS: A total of 50 male Sprague-Dawley rats were allocated to one of five groups: the control group (sham), the NxNT group (nephrectomized rats receiving no treatment), the NxFuro group (nephrectomized rats treated with furosemide), the NxCap group (nephrectomized rats treated with captopril) and the NxFuroCap group (nephrectomized rats treated with furosemide and captopril). Surgery (5/6 nephrectomy) was performed to induce CRF. Oral treatment with furosemide (20 mg/kg) and/or captopril (0.05 mg/kg) was given twice daily for 5 weeks. Parameters were studied after 5 weeks. RESULTS: In the NxNT group, arterial blood pressure was significantly increased compared with the controls. Monotherapy with furosemide or captopril and both in combination maintained blood pressure to near or below control. Myocardial and remnant-kidney calcification was detected in NxNT rats, but calcification was absent in the NxFuroCap rats. Cardiac hypertrophy and fibrosis was observed in the NxNT group but not in treatment groups. Both plasma inorganic phosphate and Ca(2+) significantly increased in the NxNT group, but the difference was not significant in the treatment groups. CONCLUSION: Furosemide, either alone or in combination with captopril, is capable to prevent myocardial calcification, cardiac hypertrophy and hypertension, maintaining blood Ca(2+) and phosphate levels by slowing CRF.

Nitrite-induced methemoglobinaemia affects blood ionized and total magnesium level by hydrolysis of plasma adenosine triphosphate in rat.

The objective of this study was to evaluate the effects of sodium nitrite (NaNO(2))-induced methemoglobinaemia on plasma ATP (adenosine triphosphate) and corresponding changes of blood-ionized magnesium (iMg(2+)) as well as total magnesium (tMg(2+)) in a time-dependent manner. This study was performed on male Sprague-Dawley rats to which NaNO(2) was injected (10 mg/kg i.p.) to induce methemoglobinaemia. Methemoglobin (MetHb) in blood was measured before (0 min.) and after 10, 30, 60 and 120 min. of NaNO(2) injection. At respective time points, the tMg(2+), blood ions and gases were measured by atomic absorption spectrometry and ion selective electrode, respectively. Haematological parameters were checked by automatic blood cell count, and blood films were observed under light microscope. Plasma ATP was measured by bioluminescence assay using a luminometer, and plasma proteins were measured by an automatic analyser. Blood cell count (RBC, WBC and platelet), haematocrit, and haemoglobin were found to be decreased with the advancement of MetHb concentration. With the gradual increase of MetHb concentration, the plasma ATP decreased and blood iMg(2+) and plasma tMg(2+) increased significantly as time passed by in comparison with the pre-drug values. A significant decrease of the ratio of ionized calcium to iMg(2+), Na(+) and increase of K(+) was observed. In conclusion, NaNO(2)-induced methemoglobinaemia is a cause of hydrolysis of plasma ATP which is responsible for the increase of blood iMg(2+) and plasma tMg(2+) in rats.