Abstract P248: The Intake Of Dried Bonito Extract May Decrease Blood Pressure Through Antioxidant Effect In 2-kidney, 1-clip Renovascular Hypertensive Rats.

Abstract

Objective: Dried bonito is a processed marine product unique to Japan, and the hot water extracted product is widely used as soup stock. It has been reported that the dried bonito extract (DBE) has antioxidants. 2-kidney, 1-clip hypertensive (2K1C) rats is an experimental model of renovascular hypertension which is known to enhance the production of oxidative stress. Plasma thiobarbituric acid reactive substances (TBARS) level, a indicator for oxidative stress, was reported to increase in 2K1C rats when compared with sham operation (SHAM) rats. Moreover, previous studies have reported that intake of a few antioxidants ameliorate hypertension in 2K1C rats. Therefore, the intake of DBE may alleviate hypertension through antioxidant effect in 2K1C rats. To test the hypothesis, in the present study, we examined the effects of dietary intake of DBE intake on blood pressure (BP) of 2K1C rats. Additionally, to investigate the mechanism, we evaluated TBARS level in plasma in those rats. Methods: Male Sprague-Dawley rats (6 wks) were treated with SHAM or clipping the left renal artery (2K1C). After surgery, the rats started receiving a control diet (CTL), a diet with 5.0% (5 of 100, w/w) DBE for 6 consecutive weeks. Systolic BP (SBP) was measured by a tail-cuff method every week. At the end of the protocol, mean arterial pressure (MAP) was measured in each rat under anesthesia. Plasma lipid peroxide levels were determined by measuring TBARS using a colorimetric method. The TBARS level was determined by the absorbance at 532 nm. Results: Analysis of variance shows that SBP was significantly higher in 2K1C-CTL (152±4 mmHg) than SHAM-CTL (131±3 mmHg) through the experiment period (P<0.001), that SBP was lower in 2K1C-DBE (147±4 mmHg) than in 2K1C-CTL (P<0.05). At the end of the protocol, MAP showed the similar trend to SBP. TBARS level in 2K1C-CTL (1.06±0.03) was significantly higher than SHAM-CTL (1.00±0.03, P<0.05). Compared with 2K1C-CTL, a significant reduction in TBARS level was observed in 2K1C-DBE (0.96±0.11, P<0.05). Conclusion: The reduction of TBARS level may contribute to a mechanism by which DBE intake decreases BP in 2K1C rats.