Hypotensive, cardiodepressant, and vasorelaxant activities of black currant (Ribes nigrum 'Ben Sarek') juice

The aim of this study was to evaluate the effects of black currant (Ribes nigrum L. 'Ben Sarek') juice on the blood pressure and frequency of cardiac contractions, as well as vasomotor responses of rat aortic rings. Arterial blood pressure was measured directly from the carotid artery in the anaesthetized rabbits. The aortic rings were pre-contracted with KCl (80 mmol.L-1),after which black currant juice was added. An intravenous injection of black currant juice (0.33-166.5 mg.kg(-1)) induced a significant and dose-dependent decrease of rabbit arterial blood pressure and heart rate. The black currant juice decreased arterial blood pressure of rabbit by 22.33% +/- 3.76% (p < 0.05) and heart rate by 17.18% +/- 2.93% (p < 0.05). Cumulative addition of the black currant juice (0.01-3 mg.kg(-1)) inhibited concentration-dependent KCl induced contractions of the isolated rat aorta. The black currant juice, at the concentration of 3 mg.kg(-1), caused a maximum relaxation of 21.75% +/- 3.15% (p < 0.05). These results demonstrate that black currant juice can induce hypotension. The hypotensive effect of the black currant may occur as the consequence of its inhibitory activity on the rate of heart contraction and vasorelaxant effects.