ABC | Volume 113, Nº5, November 2019

Original Article Vasconcelos et al. Antiarrhythmic effects of d-limonene Arq Bras Cardiol. 2019; 113(5):925-932 Figure 2 – Effect of DL (1, 5, 10, 20, and 40 mg/kg, i.v.) on heart rate (HR) and mean arterial pressure (MAP) in conscious rats. A) Original traces showing the DL effect (1, 5, 10, 20 and 40 mg/Kg, i.v., randomly) on heart rate (HR) and mean arterial pressure (MAP) from one healthy and conscious rat. The arrows indicate the moment of administration. B) Line graph of DL effect on HR and MAP. Values are mean ± SD from six experiments. Data were analysed by repeated measures two-way ANOVA followed by Bonferroni post-test. ** p < 0.01 and *** p < 0.001 vs vehicle. 150 100 50 0 20 20 30 40 10 0 20 30 40 10 0 –20 –40 –60 –80 –100 –120 –140 0 20 –20 –40 –60 –80 –100 0 5 s 1 mg/Kg 5 mg/Kg 10 mg/Kg 20 mg/Kg 40 mg/Kg MAP (mmHg) Tempo (s) % HR variation % MAP variation Vehicle ** *** *** *** *** DL Vehicle DL A B time was divided into 10, 3 min intervals for classification of arrhythmia. Arrhythmias were determined through a modified scoring system previously validated by Curtis and Walker. 16 The arrhythmias observed were ventricular premature beats (VPB), ventricular tachycardia (VT) and ventricular fibrillation (VF). VPBs < 10/3 min period were recorded as 0; VPB’s >10/3minwere recorded as 1; VT episodes of 1–5/3min were recorded as 2; > 5/3 min episodes of VT and/or any number of episodes of VF and/or 1 episode of VF with a duration < 40 s period was recorded as 3; 2-5/3 min episodes of VF or a VT and VF with a total combined with duration < 80 s period was recorded as 4; 5/3 min episodes of VF or VT and VF combined with a duration < 160 s was recorded as 5; VT or VF or both/3 min with a total combined duration < 300 s were recorded as 6, and VT or VF or both/3 min with a total combined duration > 300 s were recorded as 7. Statistical analysis The normality of the data was verified by using Shapiro- Wilk normality test. The data were represented as mean ± SD. When appropriate, it was used either unpaired Student T-test or analysis of variance (one or two way ANOVA) and Bonferroni’s post hoc test. The significance level adopted was 5% (p < 0.05). Statistical analyses were performed using GraphPad Prism TM 5.0. Results In all rats tested, HR and MAP baseline values were 371 ± 45 bpm and 114 ± 11 mmHg , respectively. Figure 2A shows original traces of the DL effect (1, 5, 10, 20, and 40 mg/kg, i.v.) on the pulsatile signal of arterial pressure of a conscious rat. In these animals, DL, at doses of 1 and 927