Abstract
Objectives:
This study aims to investigate the acute effects of thymoquinone (TQ) which has been suggested to be a cardioprotective agent, on ventricular myocytes.
Methods:
Freshly isolated rat ventricular myocytes were exposed to TQ and using standard whole-cell patch-clamp technique action potential (AP), sodium current (INa), L-type calcium current (ICaL) and transient outward potassium current (Ito) were measured.
Results:
TQ prolonged the duration of AP and decreased the peak value compared to that of control myocytes. Consistently, it inhibited INa in a concentration-dependent manner and shifted the channel kinetics to more hyperpolarized voltages. Besides, TQ not only inhibited Ito and ICaL but also significantly attenuated the isoproterenol-induced increase in ICaL.
Conclusion:
The effect of TQ on cardiomyocytes has been demonstrated for the first time. TQ changes AP morphology along with ionic currents and alleviates β-adrenergic response in adult ventricular myocytes. These results indicate that TQ may be considered as a therapeutic agent in cases such as diabetic cardiomyopathy and cardiac hypertrophy, wherein the β-adrenergic system is over-activated (Tab. 2, Fig. 6, Ref. 30).
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