Protective effects of dihydroxylphenyl lactic acid and salvianolic acid B on LPS-induced mesenteric microcirculatory disturbance in rats.

Salvia miltiorrhiza is a Chinese medicine widely used for treatment of various cardiovascular diseases. However, little is known about the role of dihydroxylphenyl lactic acid (DLA) and salvianolic acid B (SAB), the main ingredients of S. miltiorrhiza, in the microcirculation. This study aimed to investigate the effect of DLA and SAB on LPS-elicited microcirculatory disturbance, focusing especially on leukocyte adhesion and its potential mechanism. Mesenteric venular diameter, velocity of red blood cells in venules, shear rate of the venular wall, numbers of leukocytes adherent to and emigrated across the venular wall, and mast cell degranulation were determined by an inverted microscope in rats after LPS infusion with or without DLA or SAB. Expression of CD11b and CD18 and production of superoxide anion (*O2-) and hydrogen peroxide (H2O2) by neutrophils were evaluated in vitro by flow cytometry. LPS exposure induced a significant increase in the number of adherent and emigrated leukocytes and mast cell degranulation, and a prominent decrease in the velocity of red blood cells in venules and shear rate of the venular wall. Additionally, in vitro experiments revealed an apparent enhancement in expression of CD11b and CD18 and production of *O2- and H2O2 by rat neutrophils by LPS stimulation. Treatment with DLA or SAB significantly ameliorated LPS-induced microcirculatory disturbance in rat mesentery and inhibited both the expression of CD11b and CD18 and the production of *O2- and H2O2 by neutrophils caused by LPS.