A pharmaceutical preparation of Salvia miltiorrhiza protects cardiac myocytes from tumor necrosis factor-induced apoptosis and reduces angiotensin II-stimulated collagen synthesis in fibroblasts

Abstract 

Salvia miltiorrhiza is a medicinal herb commonly used in traditional Chinese medicine for the prevention and treatment of cardiovascular disease. This study investigated the effects of Cardiotonic Pill (CP), a pharmaceutical preparation of Salvia miltiorrhiza, on cardiac myocytes and fibroblasts with respect to the viability, proliferation, and collagen synthesis in these cells under various conditions. A cardiac myocyte line, H9c2, and primarily cultured fibroblasts from rat hearts were incubated with CP over a broad concentration range (50–800μg/ml) under normal cultures, conditions of ischemia (serum-free culture), and stimulation by angiotensin II (AII, 100nM), hydrogen peroxide (H₂O₂, 50–200μM), or tumor necrosis factor α (TNFα, 40ng/ml) for 24–48h. Cell growth, apoptosis, DNA and collagen synthesis, and expression of relevant genes were assessed via cell number study, morphological examination, Annexin-V staining, flow-cytometry, [³H]-thymidine or [³H]-proline incorporation assay, and Western blotting analysis. It was found that (1) at therapeutic (50μg/ml) and double therapeutic (100μg/ml) concentrations, CP did not significantly affect normal DNA synthesis and cell growth in these cardiac cells, while at higher (over 4-fold therapeutic) concentrations (200–800μg/ml), CP decreased DNA synthesis and cell growth and increased cell death; (2) CP treatment (50μg/ml) significantly inhibited TNFα-induced apoptosis in myocytes, with 12.3±1.46% cells being apoptosis in CP treatment group and 37.0±7.34% in the control (p<0.01), and simultaneously, expression of activated (phosphorylated) Akt protein was increased by about 2 folds in the CP-treated cells; and (3) in cultured fibroblasts, CP significantly reduced AII-induced collagen synthesis in a concentration-dependent manner (by ∼50% and ∼90% reduction of AII-induced collagen synthesis at 50 and 100μg/ml, respectively). Thus, Salvia miltiorrhiza preparation CP is physiologically active on cardiac cells. The actions by CP to reduce apoptotic damage in myocytes and collagen synthesis in fibroblasts may help to preserve the heart function and reduce heart failure risk. The actions by CP to inhibit DNA synthesis and cell growth, which occurred at over therapeutic doses, may weaken the ability of heart repair. Further studies are needed to identify the chemical compounds in this herbal product that are responsible for these observed physiological effects.

Keywords: Apoptosis, Cardiac myocytes, Collagen synthesis, Fibroblasts, Growth, Salvia miltiorrhiza