RESUMO
The effects of acute or chronic intake of boysenberry juice or artificial vinegar on blood pressure (BP) and endothelial function were investigated in spontaneous hypertensive rats (SHR). A single administration of boysenberry juice (BJ, equivalent to 0.5 mL/kg body weight) or artificial boysenberry juice vinegar (BJV, equivalent to 0.5 mL BJ and 0.10 g acetic acid/kg body weight) decreased both systolic blood pressure (SBP) and diastolic blood pressure (DBP) significantly. Reductions in SBP of the control group compared with the BJ and BJV groups reached maxima of -16.8±4.3 and -28.4±7.3 mmHg 8 h after administration, respectively. Chronic SBP- and DBP-lowering effects were also observed upon daily feedings of both BJ and BJV at 4 wk. No significant differences were found in SBP or DBP between respective acute and chronic intake of BJ and BJV, except for the decrease in DBP after 4 wk of BJV intake. This suggests that the polyphenol constituents in BJ and BJV likely play a major role in lowering SBP and DBP under these conditions and that acetic acid added to BJ exerts a DBP-lowering effect after 4 wk of BJV intake. The polyphenolic constituents of these beverages might elevate plasma NO concentration via aortic endothelial nitric oxide synthase activation, but the effects of chronic intake on blood pressure might also be at least partly mediated by the renin-angiotensin system. These results may help explain the beneficial effects of boysenberry intake on cardiovascular health, such as reduced blood pressure and improved endothelial function.