Abstract P169: Effects Of
Saccharina Japonica
Intake On Blood Pressure In Normotensive Rats Fed A High-salt Diet
Objectives: One of foods used for Japanese cuisine “Washoku” is brown algae, including Saccharina japonica (SJ). The intake of SJ is reported to decrease blood pressure (BP) in spontaneously hypertensive rats in some studies, and in 2-kidney, 1-clip hypertensive (2K1C) rats in our studies. Several studies indicated that dietary fibers contained in SJ, such as alginate and fucoidan, may play an important role in reducing BP. We previously demonstrated that SJ intake did not decrease BP in normotensive rats fed a normal-salt (NS) diet. We also observed that the suppression of BP rise by SJ intake was stronger in 2K1C rats fed a high-salt (HS) diet than in 2K1C rats fed an NS diet. An HS diet may lead to the development of hypertension in both humans and rats. However, to our knowledge, it has not been reported that the effect of SJ intake on BP in normotensive rats fed an HS diet. In this study, we compared the effects of SJ intake on BP between in normotensive and hypertensive rats when fed an HS diet. Methods: Male Sprague Dawley rats (6 wks) were treated with sham operation (SHAM) or clipping the left renal artery (2K1C). After surgery, rats were received a control diet (CTL) or a diet contained 5.0% (5 of 100, w/w) SJ, with an NS (0.7% NaCl) or HS (6.0% NaCl) in diets for 6 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. Results and Discussion: Analysis of variance showed that SBP was significantly higher in 2K1C-HS-CTL than in SHAM-HS-CTL (P<0.001, 156±4 vs 131±2 mmHg at the 6th week), and that SBP was lower in 2K1C-HS-SJ (146±3 mmHg) than in 2K1C-HS-CTL (P<0.05). On the other hand, there were no significant differences in SBP among SHAM groups. MAP in 2K1C-HS-CTL rats was significantly higher than that in SHAM-HS-CTL rats (153±2 vs 132±4 mmHg, P<0.005). MAP in 2K1C-HS-SJ (140±5 mmHg) rats was significantly lower than that in 2K1C-HS-CTL rats (P<0.05). There were no significant differences in MAP among SHAM groups. These findings suggested that SJ intake has an antihypertensive effect in a hypertensive model of rats, but no effect of lowering BP in a normotensive model of rats, unlike antihypertensive drugs, which reduce BP in both hypertensive and normotensive model.