RESUMO
<p><b>OBJECTIVE</b>To study the relaxant effects of glycyrrhizinate and salvianolic acid B on rat portal vein in vitro.</p><p><b>METHODS</b>Healthy female Wistar rats were canalized from hepatic artery, portal vein and hepatic vein in vitro. Remained blood in liver was eliminated with heparinized Krebs-Henseleit solution through hepatic artery, then the liver was isolated under infusing manner. Being constricted with phenylephrine and relaxed with acetylcholine, and infused with glycyrrhizinate or salvianolic acid B, the portal pressures of infused rat livers were consistently monitored by BL-420S physiological experiment system. The median effective concentration (EC50) of the two agents were analyzed with non-linear various slope regression using Prism-4 software.</p><p><b>RESULTS</b>EC50 of glycyrrhizinate in relaxing the phenylephrine-contracted portal was 1.5556 x 10(-9) mol/L, suggesting one of the mechanism of action of diammonium glycyrhizinate for the treatment of portal hypertension was direct relaxation. Salvianolic acid B showed constrictive action on the phenylephrine-retracted portal vein, the EC50 was 1.4639 x 10(-9) mol/L, indicating that its indirect control action was took part in the portal hypertension therapy synergistically.</p><p><b>CONCLUSION</b>Under the mode with both controlled-velocity and monitored pressure, glycyrrhizinate showed relaxation and salvianolic acid B showed constriction on portal pressure in vitro.</p>