Magnesium lithospermate B dilates mesenteric arteries by activating BKCa currents and contracts arteries by inhibiting KV currents

Abstract

Aim: To examine the involvement of K + channels and endothelium in the vascular effects of magnesium lithospermate B (MLB), a hydrophilic active component of Salviae miltiorrhiza Radix. Methods: Isolated rat mesenteric artery rings were employed to investigate the effects of MLB on KCl-or norepinephrine-induced contractions. Conventional whole-cell patch-clamp technique was used to study the effects of MLB on K + currents in single isolated mesenteric artery myocytes. Results: MLB produced a concentration-dependent relaxation in mesenteric artery rings precontracted by norepinephrine (1 μmol/L) with an EC 50 of 111.3 μmol/L. MLB-induced relaxation was reduced in denuded artery rings with an EC 50 of 224.4 μmol/L. MLB caused contractions in KCl-precontracted artery rings in the presence of N-nitro-L-arginine methyl ester (L-NAME) with a maximal value of 130.3%. The vasodilatory effect of MLB was inhibited by tetraethylammonium (TEA) in both intact and denuded artery rings. In single smooth muscle cells, MLB activated BK Ca currents (EC 50 156.3 μmol/L) but inhibited K V currents (IC 50 26.1 μmol/L) in a voltageand concentration-dependent manner. Conclusion: MLB dilated arteries by activating BK Ca channels in smooth muscle cells and increasing NO release from endothelium, but it also contracted arteries precontracted with KCl in the presence of L-NAME.

Magnesium lithospermate B ameliorates microcirculation perfusion in rats by promoting vascular NO production via activating the PI3K/AKT pathway

“…MLB was also shown to reduce the expression of VCAM-1 and ICAM-1 to protect endothelial function [22]. Another study confirmed that MLB could promote arterial vasodilation through the activation of BKCa channel of smooth muscle cells [23]. In the present study, we reported a novel pharmacological effect of MLB that could ameliorate microcirculation dysfunction mainly through endothelial-dependent vasodilation and NO release Fig.…”

Cardiovascular Effects of Salvianolic Acid B

“…There are at least two experiments about SalB acting on the BK Ca channel. One experiment confirmed MLB can make arterial vasodilating through the activation of BK Ca channel (big-conductance Ca 2+ -activated K + channels) of smooth muscle cell and the increase of endothelial NO release [54]. Another one verified that salvianolic acid B could activate the opening of the BK Ca channels of the porcine coronary artery smooth muscle cells.…”

Study on Relieving Cerebral Injury of CPB Rats by Danhong Injection

“…Danhong injection is a compound preparation extracted from salvia miltiorrhiza and safflower [2] . Compared with conventional traditional Chinese medicine, traditional Chinese medicine injection has the advantages of fast and explicit effect.…”