The contraction of hepatic stellate cells (HSCs) has a critical role in the regulation of intrahepatic vascular resistance and
portal hypertension. Previous studies have confirmed that
salvianolic acid B (Sal B) is effective against
liver fibrosis. In the present study, we evaluated the effect of Sal B on
portal hypertension and on HSCs contractility.
Liver cirrhosis was induced in rats by peritoneal injection of
dimethylnitrosamine and the portal pressure was measured. HSCs contraction was evaluated by
collagen gel contraction assay.
Glycerol-
urea gel electrophoresis was performed to determine the phosphorylation of
myosin light chain 2 (MLC2).
F-actin stress fiber polymerization was detected by
fluorescein isothiocyanate-labeled
phalloidin. Intracellular Ca(2+) and RhoA signaling activation were also measured. Sal B effectively reduced the portal pressure in DMN-induced cirrhotic rats. It decreased the contraction by
endothelin-1 (ET-1)-activated HSCs by ∼66.5% and caused the disassembly of actin stress fibers and MLC2 dephosphorylation. Although Sal B reduced ET-1-induced intracellular Ca(2+) increase, blocking Ca(2+) increase completely by
BAPTA-AM, a Ca(2+)
chelator, barely affected the magnitude of contraction. Sal B decreased ET-1-induced RhoA and Rho-associated coiled coil-forming
protein kinase (ROCK) II activation by 66.84% and by 76.79%, respectively, and inhibited Thr(696) phosphorylation of MYPT1 by 80.09%. In vivo, Sal B lowers the portal pressure in rats with DMN-induced
cirrhosis. In vitro, Sal B attenuates ET-1-induced HSCs contraction by inhibiting the activation of RhoA and ROCK II and the downstream MYPT1 phosphorylation at Thr(696). We consider Sal B a potential candidate for the pharmacological treatment of
portal hypertension.