To investigate the effects of total alkaloids of Aconitum carmichaelii on myocardial function in rats and its underlying mechanisms.

SPF-grade Wistar rats were randomly assigned into five groups (n=10 each): blank group (0.9% NaCl), control group (isoproterenol 10 mg·kg^-1), experimental-L group (2.72 g·kg^-1 total alkaloids of A. carmichaelii), experimental-M group (3.68 g·kg^-1), and experimental-H group (4.98 g·kg^-1). All groups were gavaged once daily for 5 consecutive days. Thirty minutes after the last injection, T-wave amplitude on electrocardiogram was recorded. An isolated heart perfusion model was established to evaluate cardiac function and myocardial contractility. Myocardial cell activity and malondialdehyde content were measured, and real-time quantitative PCR was used to detect mRNA expression levels of peroxisome proliferator-activated receptor gamma coactivator-1 alpha (Pgc-1α), B-cell lymphoma 2 (Bcl-2) and Bcl-2-associated X protein (Bax).

The T-wave amplitudes for the experimental -L, -M, -H groups, blank group and control group were (0.17±0.07), (0.29±0.05), (0.37±0.04), (0.30±0.07) and (0.36±0.04) mV, respectively; the myocardial cell activities were (0.46±0.05), (0.44±0.08), (0.35±0.07), (0.45±0.06) and (0.33±0.05) Abs, respectively; the while malondialdehyde contents were (2.56±0.28), (2.55±0.26), (2.86±0.28), (2.49±0.34) and (2.83±0.25) mmol·mL^-1, respectively; the relative mRNA expression levels of Pgc-1α were 0.49±0.05, 0.41±0.07, 0.27±0.05, 0.48±0.06 and 0.35±0.05, respectively; the relative mRNA expression levels of Bax were 1.10±0.08, 1.25±0.09, 1.36±0.07, 1.09±0.09 and 1.33±0.07, respectively; the relative mRNA expression levels of Bcl-2 were 0.58±0.06, 0.51±0.05, 0.44±0.04, 0.56±0.08 and 0.45±0.03, respectively. Compared with the experimental -M, -H groups and blank group, the above indexes of the experimental -L group were statistically significant (all P<0.05).

Lower doses of Aconitum carmichaelii total alkaloids positively influence ECG T-wave amplitude, cardiac function, and myocardial contractility, improve myocardial cell activity, and reduce oxidative stress, whereas high doses exert cardiotoxic effects.