Background: Shensong Yangxin Capsule (SSYX), traditional Chinese medicine, has been used to treat arrhythmias, angina, cardiac remodeling, cardiac fibrosis, and so on, but its effect on cardiac energy metabolism is still not clear. The objective of this study was to investigate the effects of SSYX on myocardium energy metabolism in angiotensin (Ang) II-induced cardiac hypertrophy. Methods: We used 2 mu l (10(-6) mol/L) AngII to treat neonatal rat cardiomyocytes (NRCMs) for 48 h. Myocardial alpha-actinin staining showed that the myocardial cell volume increased. Expression of the cardiac hypertrophic marker-brain natriuretic peptide (BNP) messenger RNA (mRNA) also increased by real-time polymerase chain reaction (PCR). Therefore, it can be assumed that the model of hypertrophic cardiomyocytes was successfully constructed. Then, NRCMs were treated with 1 mu l of different concentrations of SSYX (0.25, 0.5, and 1.0 mu g/ml) for another 24 h. To explore the time-depend effect of SSYX on energy metabolism, 0.5 mu g/ml SSYX was added into cells for 0, 6, 12, 24, and 48 h. Mitochondria was assessed by MitoTracker staining and confocal microscopy. mRNA and protein expression of mitochondrial biogenesis-related genes - Peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1 alpha), energy balance key factor - adenosine monophosphate-activated protein kinase (AMPK), fatty acids oxidation factor - carnitine palmitoyltransferase-1 (CPT-1), and glucose oxidation factor - glucose transporter- 4 (GLUT-4) were measured by PCR and Western blotting analysis. Results: With the increase in the concentration of SSYX (from 0.25 to 1.0 mu g/ml), an increased mitochondrial density in AngII-induced cardiomyocytes was found compared to that of those treated with AngII only (0.25 mu g/ml, 18.3300 +/- 0.8895 vs. 24.4900 +/- 0.9041, t = 10.240, P < 0.0001; 0.5 mu g/ml, 18.3300 +/- 0.8895 vs. 25.9800 +/- 0.8187, t = 12.710, P < 0.0001; and 1.0 mu g/ml, 18.3300 +/- 0.8895 vs. 24.2900 +/- 1.3120, t = 9.902, P < 0.0001; n = 5 per dosage group). SSYX also increased the mRNA and protein expression of PGC-1 alpha (0.25 mu g/ml, 0.8892 +/- 0.0848 vs. 1.0970 +/- 0.0994, t = 4.319, P = 0.0013; 0.5 mu g/ml, 0.8892 +/- 0.0848 vs. 1.2330 +/- 0.0564, t = 7.150, P < 0.0001; and 1.0 mu g/ml, 0.8892 +/- 0.0848 vs. 1.1640 +/- 0.0755, t = 5.720, P < 0.0001; n = 5 per dosage group), AMPK (0.25 mu g/ml, 0.8872 +/- 0.0779 vs. 1.1500 +/- 0.0507, t = 7.239, P < 0.0001; 0.5 mu g/ml, 0.8872 +/- 0.0779 vs. 1.2280 +/- 0.0623, t = 9.379, P < 0.0001; and 1.0 mu g/ml, 0.8872 +/- 0.0779 vs. 1.3020 +/- 0.0450, t = 11.400, P < 0.0001; n = 5 per dosage group), CPT-1 (1.0 mu g/ml, 0.7348 +/- 0.0594 vs. 0.9880 +/- 0.0851, t = 4.994, P = 0.0007, n = 5), and GLUT-4 (0.5 mu g/ml, 1.5640 +/- 0.0599 vs. 1.7720 +/- 0.0660, t = 3.783, P = 0.0117; 1.0 mu g/ml, 1.5640 +/- 0.0599 vs. 2.0490 +/- 0.1280, t = 8.808, P < 0.0001; n = 5 per dosage group). The effect became more obvious with the increasing concentration of SSYX. When 0.5 mu g/ml SSYX was added into cells for 0, 6, 12, 24, and 48 h, the expression of AMPK (6 h, 14.6100 +/- 0.6205 vs. 16.5200 +/- 0.7450, t = 3.456, P = 0.0250; 12 h, 14.6100 +/- 0.6205 vs. 18.3200 +/- 0.9965, t = 6.720, P < 0.0001; 24 h, 14.6100 +/- 0.6205 vs. 21.8800 +/- 0.8208, t = 13.160, P < 0.0001; and 48 h, 14.6100 +/- 0.6205 vs. 23.7400 +/- 1.0970, t = 16.530, P < 0.0001; n = 5 per dosage group), PGC-1 alpha (12 h, 11.4700 +/- 0.7252 vs. 16.9000 +/- 1.0150, t = 7.910, P < 0.0001; 24 h, 11.4700 +/- 0.7252 vs. 20.8800 +/- 1.2340, t = 13.710, P < 0.0001; and 48 h, 11.4700 +/- 0.7252 vs. 22.0300 +/- 1.4180, t = 15.390; n = 5 per dosage group), CPT-1 (24 h, 15.1600 +/- 1.0960 vs. 18.5800 +/- 0.9049, t = 6.048, P < 0.0001, n = 5), and GLUT-4 (6 h, 10.2100 +/- 0.9485 vs. 12.9700 +/- 0.8221, t = 4.763, P = 0.0012; 12 h, 10.2100 +/- 0.9485 vs. 16.9100 +/- 0.8481, t = 11.590, P < 0.0001; 24 h, 10.2100 +/- 0.9485 vs. 19.0900 +/- 0.9797, t = 15.360, P < 0.0001; and 48 h, 10.2100 +/- 0.9485 vs. 14.1900 +/- 0.9611, t = 6.877, P < 0.0001; n = 5 per dosage group) mRNA and protein increased gradually with the prolongation of drug action time. Conclusions: SSYX could increase myocardial energy metabolism in AngII-induced cardiac hypertrophy. Therefore, SSYX might be considered to be an alternative therapeutic remedy for myocardial hypertrophy.