Abstract P385: The Enhanced Antihypertensive Effect by a Combination Diet of Allium Bakeri and Capsaicin in 2-Kidney, 1-Clip Renovascular Hypertensive Rats

Abstract

Objective: Allicin contained in Allium Bakeri (AB) , a transient receptor potential (TRP) vanilloid type-1 (TRPV1) and TRP ankyrin-1 (TRPA1) agonist, increases phosphorylated (p-) endothelial nitric oxide synthase (eNOS). Another TRPV1 agonist, capsaicin (CAP), causes a vasodilatory effect through the increment of p-eNOS. We recently demonstrated the alleviation of blood pressure (BP) elevation by each intake of AB and CAP in 2-kidney, 1-clip (2K1C) hypertensive rats. AB is often used with red hot chili pepper containing CAP in the Japanese cuisine. We hypothesized that a combination diet of AB and CAP enhances the antihypertensive effect compared with each diet. In this study, to test the hypothesis, we investigated the interactive effects of dietary AB and CAP on BP, as well as the p-eNOS/eNOS in the protein expression of aorta, in 2K1C rats. Method: Male Sprague-Dawley rats (6wks) were treated with sham operation (SHAM) or clipping the left renal artery (2K1C). After surgery, SHAM rats received a control diet (CTL), and 2K1C rats received CTL, a diet with 1% (10 of 1,000, w/w) freeze-dried AB powder, with 0.006% (60 of 1,000,000, w/w) CAP or with both (AB+CAP) for 6 weeks. The systolic BP (SBP) was measured by a tail-cuff method once per week. At the end of protocol, rats were euthanized and the thoracic aortas were collected for extracting the protein. The p-eNOS/eNOS in the protein expression in aorta was evaluated by Western blotting. Result: Analysis of variance showed that SBP was significantly higher in 2K1C-CTL than SHAM-CTL through the protocol (123±2.3 vs 165±3.2 mmHg, p < 0.05, at 6 weeks after the surgery). SBP was lower in 2K1C-AB and -CAP in 2K1C-CTL (151±2.4 and 139±3.7 vs 165±3.2, p < 0.05, each). Compared with 2K1C-AB and -CAP, a significant reduction in SBP was observed in 2K1C-AB+CAP (135±3.1, at 6 weeks) throughout the procedure ( p < 0.05). The p-eNOS/eNOS was tended to be enhanced in 2K1C-AB and -CAP, but not in 2K1C-AB+CAP, compared to 2K1C-CTL. Conclusion: A combination diet of AB and CAP may enhance antihypertensive effects compared with each diet of AB and CAP, in 2K1C rats. Although the increase in eNOS phosphorylation may participate in the mechanism of the antihypertensive effects by each diet of AB and CAP, it may not do in that of their combined effect.