Inhibition of endothelium-dependent vascular relaxation by tetrandrine

The effects of tetrandrine, a Ca2+ antagonist of bis-benzylisoquinoline alkaloid origin, on endothelium-dependent and -independent vascular responsiveness were investigated in perfused rat mesenteric artery. In endothelium-intact preparations pre-contracted with 3 microM phenylephrine and fully relaxed by 0.3 microM acetylcholine tetrandrine caused a rapid transient contraction. In endothelium-denuded preparations, tetrandrine caused only …