Endothelium-independent vasorelaxation by leonurine, a plant alkaloid purified from Chinese motherwort

Leonurine, a plant alkaloid present in Chinese motherwort, induced concentration- dependent and endothelium-independent relaxation of phenylephrine (PE)- pretreated rat aortic arterial rings. The IC50 values for leonurine were 86.4+/-10.4 and 85.9+/-17.2 microM in the presence and absence of endothelium respectively. It inhibited the responses of aortic smooth muscle to PE in Ca2+ free medium containing 100 microM EGTA, suggesting a possible …