Effect of sodium tanshinone II a sulfonate on phosphorylation of extracellular signal-regulated kinase1/2 in angiotensin II-induced hypertrophy of myocardial cells

Objective: To observe the effects of sodium tanshinone R A sulfonate (STS) on angiotensin II (Ang II)-induced hypertrophy of myocardial cells through the expression of phosphorylated extracellular signal-regulated kinase (p-ERK1/2). Methods: In the primary culture of neonatal rat myocardial cells, the total protein content in myocardial cells was determined by coomassie brilliant blue and the protein synthesis rate was measured by [3H]-Leucine incorporation as indexes for hypertrophy of myocardial cells. The expression of p-ERK1/2 was determined using Western blot and immunofluorescence labeling. Results: (1) The total protein and protein synthesis rate increased significantly in contrast to the control group after the myocardial cells were stimulated by Ang II (1 mu mol/L) for 24 h; STS markedly inhibited the increment of the total protein level induced by Ang II and the syntheses of protein. (2) After pretreatment of myocardial cells with Ang II (1 mu mol/L) for 5 min, the p-ERK1/2 protein expression was increased, with the most obvious effect shown at about 10 min; pretreatment of myocardial cells with STS at different doses (2, 10, 50 mu mol/L) for 30 min resulted in obvious inhibition of the expression of p-ERK1/2 stimulated by Ang II in a dose-dependent manner. (3) After the myocardial cells were stimulated by Ang II (1 mu mol/L), the immunofluorescence of ERK1/2 rapidly appeared in the nucleus. The activation and translocation process of ERK1/2 induced by Ang II was blocked distinctly by STS. Conclusion: STS inhibited the myocardial cell hypertrophy induced by Ang II, and the mechanism may be associated with the inhibition of p-ERK1/2 expression.