Nitric oxide synthase activity in blood vessels of spontaneously hypertensive rats: antioxidant protection by gamma-tocotrienol

• Autorzy: Newaz M.A. , Yousefipour Z. , Nawal N. , Adeeb N.
• Języki publikacji: EN

Abstrakty

EN

Involvement of free radicals and nitric oxide (NO) has long been implicated to the pathogenesis of essential hypertension. Several studies using antioxidants as the radical scavenger have shown to confer protection against free radical mediated diseases. This study is designed to investigate the role of antioxidant -tocotrienol on endothelial nitric oxide synthase (NOS) activity in spontaneously hypertensive rats (SHR). SHR's were divided into four groups namely untreated SHR (HC), treatment with 15mg -tocotrienol/kg diet (l), 30mg -tocotrienol/kg diet (2) and 150mg -tocotrienol/kg diet (3) and studied for three months. Wister Kyoto (WKY) rats were used as the control (C). Blood pressure was recorded every fortnightly by tail plethysmography. Animals were sacrificed and NOS activity in blood vessels was measured by [3H]arginine radioactive assay. Nitrite concentration in plasma was determined by Greis assay and lipid peroxides in the blood vessels by spectrofluorometry. This study showed that -tocotrienol significantly reduced systolic blood pressure (SBP) in SHRs with a maximum reduction in group treated with -tocotrienol 15 mg/kg diet (HC: 210±9 mmHg, l:123±19 mmHg). Blood vessels from untreated SHR showed a reduced NOS activity compare to that of WKY rats (C: 1.54±0.26 pmol/mg protein, HC: 0.87+0.23pmol/mg protein; p,0.001). -tocotrienol improves NOS activity in all the groups with more significance in group 2 (p<0.001) and 3 (p<0.05). Plasma level of nitrite was reduced in SHR from 55±3 µM/ml in WKY to 26±2 µM/ml (p<0.001). Plasma nitrite level was reversed by treatment with -tocotrienol. (l: p<0.001, 2: p<0.005, 3: p<0.001, respectively). In all the treatment groups, NOS activity showed significant negative correlation with blood pressure (l: r=-0.716, p<0.05; 2: r=-0.709, p<0.05; 3: r=-0.789, p<0.05). For plasma nitrite, although it shows a negative correlation with blood pressure it was significant only in l (r=-0.676, p<0.05) and 2 (r=-0.721, p<0.05). From this study we found that compared to WKY rats, SHR has lower NOS activity in blood vessels, which upon treatment with antioxidant -tocotrienol increased the NO activity and concomitantly reduced the blood pressure. These findings further strengthen the hypothesis that free radicals and NO play critical role in pathogenesis of essential hypertension.

Słowa kluczowe

EN

blood vessel; nitric oxide synthase; gamma-tocotrienol; hypertension; free radical; antioxidant; rat; blood pressure

• Wydawca: -
• Czasopismo: Journal of Physiology and Pharmacology
• Rocznik: 2003
• Tom: 54
• Numer: 3
• Opis fizyczny: p.319-327,fig.,ref.

Twórcy

autor

Newaz M.A.

• Texas Southern University, 3100 Cleburne Avenue, Houston, TX 77004, USA

autor

Yousefipour Z.

autor

Nawal N.

autor

Adeeb N.