Nongenomic activation of the GC-A enzyme by resveratrol and estradiol downstream from membrane estrogen receptors in human coronary arterial cells.

Background And Aim: Resveratrol (RSVL), a polyphenolic phytoestrogen in grapes, confers multifaceted cardiovascular benefits. The cellular and molecular basis of RSVL actions has been largely undefined until now.

Methods And Results: In human coronary smooth muscle cells (HCSMCs), RSVL markedly (3.2-fold) enhanced cGMP formation (t(1/2): 6.3 min, EC(50): 1.8 microM) and stimulated kinase-G activity (4-fold). By contrast, RSVL had no effect on cAMP or PKA activity in these cells. The RSVL-enhanced cGMP/kinase-G activity was not abrogated by the nitric oxide synthase-inhibitor (L-NMMA, 10 microM), or the soluble guanylyl cyclase (sGC)-inhibitor (ODQ, 10 microM). In membrane preparations from HCSMCs, RSVL activated GC in the particulate-, but not in the soluble-membrane fraction. Similar effects were due to the specific particulate-GC-A agonist atrial natriuretic peptide (ANP, 0.1-1 microM). The combined effects of RSVL and ANP were competitive. By contrast, the selective GC-B agonist (BNP) showed no response on cGMP, whereas that for GC-C (guanylin) produced only slight increases in cGMP levels. Estradiol (E2) mimicked the effects of RSVL on cGMP, but showed a 46% lower maximal response. Combining E2 with RSVL showed a competitive, rather than an additive, response. Further, cGMP formation by RSVL or E2 was significantly attenuated by the pure estrogen receptor blocker, ICI-182,780 (10 microM).

Conclusion: These findings are the first to link RSVL with pGC/kinase-G activation downstream from membrane ERs in the vasculature, thus substantiating its coronary protective effects, even in endothelium-disrupted coronary arteries.