Ingestion of cocoa ameliorates endothelial dysfunction in mesentery arterioles induced by high fat diet in rats: an in vivo intravital microscopy study.

Numerous clinical studies have reported that ingestion of cocoa has a therapeutic effect on hypertension. However, there is only limited information on the mechanism of ingestion of cocoa on arterioles, vessels that have a major role in determining blood pressure. In this study, we used intravital video-microscopy to evaluate the effect of cocoa consumption on the mesentery microcirculation of rats fed a high fat diet. The animals were allocated to 3 groups, and fed either a control diet, a high fat diet containing 15% lard, or the HFD with 2% cocoa (HFD-C) for 6 weeks. At the end of the experimental period, the mesentery was spread in a chamber, and the vessels were treated topically with phenylephrine, acetylcholine, or papaverine. The vascular responses to phenylephrine, acetylcholine-dependent vasodilatation and endothelium-independent vasodilatation were calculated by the diameter of the mesentery artery with each treatment. Topical treatment of mesenteric arterioles with acetylcholine caused a significantly greater response in the control compared with the HFD group. In the HFD-C group, acetylcholine-dependent vasodilatation was decreased marginally. Similarly, rats in the HFD group showed a significant reduction in vascular sensitivity to phenylephrine compared with the control group. However, there was no significant difference between the control and HFD-C groups. The induction of endothelial-independent artery dilation was reduced slightly in the HFD group. Our results suggest that one of the hypotensive mechanisms of cocoa is due to amelioration of endothelial dysfunction in arterioles induced by an inappropriate diet.