In this study, it was surveyed to know whether an oral single dose of oleuropein could mimic the cardiac preconditioning in rats’ hearts or whether its prolonged oral administration could protect the heart against the ACONITINE-induced arrhythmia in rats.Eighty male Wistar rats were divided into two series (n=8 in each group). In the first series, all groups (except the control (Con) group) were given a single oral dose of oleuropein (20 mg/Kg) 1, 3, 24 and 48 h before the infusion of ACONITINE. In the second series, except the Con group, the other four groups were given oral oleuropein (20 mg/Kg/day) for 3, 7, 14 and 28 days, before the infusion of ACONITINE. Electrocardiogram was recorded to monitor arrhythmia.Data of the first series showed that the initiation time of arrhythmia, the initiation of ventricular tachycardia (VT), the numbers of reversible ventricular fibrillation (VF) and the death time had no significant difference compared with Con group. In the second series, a significant protection was occurred only in the 28 days group that was evident with increased initiation time of arrhythmia, increased initiation time of VT, and increased the number of reversible VF and death time in compared to the Con group.The findings of this study show that the oral administration of a single dose of oleuropein could not mimic the preconditioning effects in rat hearts, but the prolonged administration of oleuropein for about four weeks could protect the heart against ACONITINE-induced arrhythmia.

Background and Aim: Previous studies have shown that carvacrol has hypotensive, bradycardic and calcium inhibitory effects. Since the opening of calcium channels have an important role in the incidence of arrhythmias, this study aimed to investigate whether carvacrol has anti-arrhythmic effects against ACONITINEinduced arrhythmia or not.Materials and Methods: In this experimental study, s eventy male Wistar rats were divided into seven groups of ten: Group 1 as the control Group; Group 2 as the pretreatment with lidocaine (10 mg/kg); Group 3 and 4 as the pretreatment with carvacrol 10 and 50 mg/kg; Group 5 as the treatment with lidocaine (10 mg/kg); and Group 6 and 7 as the treatment with carvacrol 50 μg/kg. Lidocaine and carvacrol were infused intravenously as pretreatment and treatment respectively before and after the infusion of ACONITINE (as an arrhythmic substance). Ventricular arrhythmia including the onset of arrhythmia, incidence percentage of ventricular tachycardia and fibrillation, and irreversible ventricular fibrillation and atrial fibrillation were monitored following the infusion of ACONITINE for 30 minutes. Data were analyzed in GraphPad Prism statistical software by one-way ANOVA, Tukey’s post hoc test, and Fisher’s exact test.Results: Data showed that the magnitude of ventricular arrhythmia including the onset of arrhythmia, incidence percentage of ventricular tachycardia and fibrillation, and irreversible ventricular fibrillation significantly reduced in pretreatment and treatment groups with lidocaine. It also reduced markedly in pretreatment and treatment groups with carvacrol 50 mg/kg, although not as much as in the lidocaine group.There was not any significant difference between carvacrol 10 mg/kg groups and control group both in pretreatment and treatment protocol.Conclusion: The findings of this study indicate that the maximum dose of carvacrol which did not have any significant effect on blood pressure reduced the magnitude of ACONITINE-induced arrhythmia. This may use prevention and alternative of cardiac arrhythmias.

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.