Acute effect of thymoquinone on action potential and ionic currents of rat cardiac myocytes

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 (I Na ), L-type calcium current (I CaL ) and transient outward potassium current (I to ) were measured. RESULTS: TQ prolonged the duration of AP and decreased the peak value compared to that of control myocytes. Consistently, it inhibited I Na in a concentration-dependent manner and shifted the channel kinetics to more hyperpolarized voltages. Besides, TQ not only inhibited I to and I CaL but also signifi cantly attenuated the isoproterenol-induced increase in I CaL . CONCLUSION: The effect of TQ on cardiomyocytes has been demonstrated for the fi rst 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).

Thymoquinone Produces Cardioprotective Effect in β-Receptor Stimulated Myocardial Infarcted Rats via Subsiding Oxidative Stress and Inflammation

“…In another study, the long-term administration of oral TQ induced a positive inotropic effect in rats [14]. However, in a very recent study, the acute effects of TQ showed to exert cardioprotective effects on ventricular myocytes, and suggested as a therapeutic agent in diabetic cardiomyopathy and cardiac hypertrophy, which involves the over-activated β-adrenergic system [15]. The potent activity of TQ encouraged us to investigate its acute effects in the ISO-induced experimental animal model of MI.…”