Antifibrotic effects of magnesium lithospermate B on hepatic stellate cells and thioacetamide-induced cirrhotic rats

Magnesium lithospermate B (MLB) is one of the major active components of Salvia miltiorrhizae. The anti-oxidative effects of Salvia miltiorrhizae have been previously reported. The aim of this study was to investigate the effect of purified MLB on hepatic fibrosis in rats and on the fibrogenic responses in hepatic stellate cells (HSCs). Hepatic fibrosis was induced in rats by intraperitoneal thioacetamide (TAA) injections over a period of 8 or 12 weeks. MLB was orally administered daily by gavage tube. Serum AST and ALT levels in TAA + MLB group were significantly lower than those in TAA only group at week 8. Hepatic fibrosis was significantly attenuated in TAA + MLB group than in TAA only group at week 8 or 12. Activation of HSCs was also decreased in TAA + MLB group as compared to TAA only group. Hepatic mRNA expression of alpha-smooth muscle actin (alpha-SMA), TGF-beta1, and collagen alpha1(I) was significantly decreased in TAA + MLB group as compared to TAA only group. Incubation with HSCs and MLB (> or =100 microM) for up to 48 h showed no cytotoxicity. MLB suppressed PDGF-induced HSC proliferation. MLB inhibited NF-kappaB transcriptional activation and monocyte chemotactic protein 1 (MCP-1) production in HSCs. MLB strongly suppressed H2O2-induced reactive oxygen species (ROS) generation in HSCs, and MLB inhibited type I collagen secretion in HSCs. We concluded that MLB has potent antifibrotic effect in TAA-treated cirrhotic rats, and inhibits fibrogenic responses in HSCs. These data suggest that MLB has potential as a novel therapy for hepatic fibrosis.

Magnesium lithospermate B inhibits intracellular calcium elevation induced by ATP and KCl in rat vascular smooth muscle cells / 中国药理学通报

Aim To investigate the effects of magnesium lithospermate B(MLB) on vasoconstriction of denuded aortic rings in vitro,as well as the effects of MLB on cytosolic free calcium concentration([Ca~(2+)]_i) in aortic vascular smooth muscle cells(AVSMCs).Methods Isotonic tension was measured in the rat thoracic aortic rings without endothelium and quantitative changes of [Ca~(2+)]_i were directly monitored in AVSMCs loaded with the fluorescent calcium indicator Fluo-3 using intracellular cation measurement system.Results MLB had no effects on resting ring tension in the presence or absence of extracellular Ca~(2+).In rings exposed to 50～200 ?mol?L~(-1) MLB,the isotonic contractions induced by 1 ?mol?L~(-1) PE were decreased in calcium-free K-H solution.However,in the presence of extracellular Ca~(2+),KCl 60 mmol?L~(-1) produced isotonic contractions that were abolished by verapamil 10 ?mol?L~(-1) or inhibited by pretreatment of 50～200 ?mol?L~(-1) MLB in a concentration-dependent manner.When administered to the rings precontracted with 1 ?mol?L~(-1) PE in the absence of extracellular Ca~(2+),a second extracelluar-calcium-dependent vasoconstriction induced by restoration of extracellular Ca~(2+) was also reduced by pretreatment of 50～200 ?mol?L~(-1) MLB.Moreover,MLB,at concentration of 50～200 ?mol?L~(-1),produced little effect on AVSMCs [Ca~(2+)]_i in the presence or absence of extracellular Ca~(2+).In AVSMCs exposed to 50～200 ?mol?L~(-1) MLB,the inhibitory effects of MLB on [Ca~(2+)]_i induced by 20 ?mol?L~(-1) ATP were concentration-dependent,with decreases ranging from 17.4% to 61.1% in the absence of extracellular Ca~(2+).In the presence of extracellular Ca~(2+) and thapsigargin,the increases in AVSMCs [Ca~(2+)]_i evoked by 60 mmol?L~(-1) KCl were inhibited by pretreatment with MLB(50～200 ?mol?L~(-1)) or abolished by pretreatment with verapamil(10 ?mol?L~(-1)).Conclusions MLB inhibits vasoconstriction induced by PE,high-K~+,and re-Ca~(2+).MLB also has inhibitory effects on increase of [Ca~(2+)]_i induced by ATP and high K~+ in AVSMCs.These results indicate that both the blocking effects on calcium release and voltage-dependent calcium channels may be responsible for the effects of MLB on [Ca~(2+)]_i in vascular smooth muscle cells.