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

AIMS: 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.

MAIN METHODS: 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.

KEY FINDINGS: 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.

SIGNIFICANCE: 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.