Mechanisms underlying the vasorelaxation of human internal mammary artery induced by (-)-epicatechin

(−)‐Epicatechin‐induced relaxation of isolated human saphenous vein: Roles of K+ and Ca2+ channels

“…Endothelial denudation did not significantly influence the relaxing response to (−)‐epicatechin, suggesting involvement of endothelium‐independent mechanisms in its action on this blood vessel. These results are in accordance with previously reported findings on the rat aorta (Duarte et al, ) and HIMA (Novakovic et al, ).…”

“…Reported potencies were usually in micromollar ranges, but may vary according to flavonoids, as well as with vessels. For example, (−)‐epicatechin concentrations producing half‐maximal relaxation of HIMA (7.4 and 13.8 μM) and HSV (44.6 and 57.5 μM) with and without endothelium, respectively, indicate quite more sensitivity of HIMA to this flavanol (Novakovic et al, ). Comparing with (−)‐epicatechin, potency of flavonoid dioclein, tested only on HSV, was ~4 times greater (EC 50 = 11.1 μM; Gonçalves et al, ), whereas (−)‐epicatechin dimer, procyanidin B2 (epicatechin‐(4β → 8)‐epicatechin), was ~70 times more potent in relaxing HIMA (EC 50 = 0.1 μM) then pure (−)‐epicatechin (Novakovic et al, ).…”

“…We have previously shown that (−)‐epicatechin produced relaxation of the isolated human internal mammary artery (HIMA) by activation of 4‐aminopyridine (4‐AP)‐ and margatoxin‐sensitive voltage‐gated K + (K V ) channels, as well as large‐conductance Ca 2+ ‐activated K + (BK Ca ) and ATP‐sensitive K + (K ATP ) channels located in vascular smooth muscle. In addition, we have shown that (−)‐epicatechin could inhibit influx of extracellular Ca 2+ , interfere with intracellular Ca 2+ release and reuptake by the sarcoplasmic reticulum (Novakovic et al, ). Other authors suggest that endothelium‐independent relaxation induced by (−)‐epicatechin is mediated by inhibition of Ca 2+ influx through voltage‐gated Ca 2+ channels in vascular smooth muscle (Huang et al, ).…”

(−)-Epicatechin Prevents Blood Pressure Increase and Reduces Locomotor Hyperactivity in Young Spontaneously Hypertensive Rats

“…Regarding vascular function, acute Epi administration induces both endothelium-dependent and endothelium-independent relaxation in the isolated arteries of normotensive rats and in human arteries [49–51]. The Epi-induced endothelium-dependent relaxation in normotensive rats was primarily mediated by NO [49, 50].…”

A review on the structure-activity relationship of dietary flavonoids for protecting vascular endothelial function: Current understanding and future issues

“…This may be attributed to a direct antioxidant effect of (−)‐epicatechin in endothelial cells (Ruijters, Weseler, Kicken, Haenen, & Bast, ). To date, however, no evidence has clarified that unmetabolized (−)‐epicatechin has a direct action of NO regulation in unstimulated (resting) endothelial cells or in isolated aortic rings, even though (−)‐epicatechin is enable to induce the strong endothelium‐independent relaxation in internal mammary artery model (Novakovic et al, ).…”