Arrhythmogenic Risk Assessment Following Four-Week Pretreatment With Nicotine and Black Tea in Rat

BACKGROUND: There is the controversy concerning the main component of tobacco, which is responsible for its arrhythmogenesis. In addition, there is the lack of adequate information about the influence of combination of black tea and nicotine on heart rhythm. OBJECTIVES: This study aimed to examine whether pretreatment with black tea and nicotine could modulate the susceptibility to lethal ventricular arrhythmias. MATERIALS AND METHODS: Animals were randomized to control, black tea, nicotine, and black tea plus nicotine groups. Test groups were treated with black tea brewed (orally) and nicotine (2 mg/kg, subcutaneous), alone and in combination for four weeks. On day 29, aconitine was infused intravenously for induction of cardiac arrhythmia. RESULTS: In comparison with the control group, each of tea and nicotine significantly decreased the duration of the ventricular tachycardia (VT) plus ventricular fibrillation (VF) and the score of arrhythmia severity (P < 0.05 and P < 0.01, respectively,). The latency for the first VT event was significantly longer in the all test groups, but VF latency was significant only in tea and nicotine groups compared with control group (P < 0.05 and P < 0.01, respectively).Threshold dose of aconitine for inducing VT and VF increased in all test groups, but only VT showed a significant difference in comparison to the control group (P < 0.001). CONCLUSIONS: The findings suggest that sub-chronic consumption of nicotine or black tea alone with appropriate doses could potentially be antiarrhythmic and its combination regimen does not increase the risk of fatal ventricular arrhythmias during four-week consumption period in rats.