In vivo hemodynamic and electrocardiographic changes following Crataegus aronia syn. Azarolus (L) administration to normotensive Wistar rats

Objectives: To evaluate the effects of the whole plant aqueous extract of Crataegus aronia (C. aronia) syn. Azarolus (L) on the hemodynamic and electrocardiographic intervals in albino rats. Methods: This study was carried out in 2 stages at the Research Laboratory, Physiology Department, Medical College of King Khalid University, Abha, Kingdom of Saudi Arabia between February and June 2012. First, the effects of C. aronia syn. Azarolus (L) on the hemodynamics and electrocardiograph in 54 Wistar male rats were assessed, then the mechanisms underlying the hemodynamic and electrocardiographic changes observed in the first stage were evaluated in 48 rats of the same species. Results: The C. aronia administered at escalating doses (0.05-20 μg/kg) produced a dose-time-dependent decrease in heart rate (HR) and mean arterial pressure (MAP). Higher doses (15 and 20 μg/kg) produced the most significant reduction in both HR and MAP, and induced sinus node suppression and progressive atrio-ventricular blockade. The underlying mechanism of the induced bradyarrhythmia appeared to be due to the direct stimulation of the muscarinic receptor M2 and possible blockade of beta-receptors, while the hypotension was caused by enhanced nitric oxide release. No significant alterations in the electrocardiogram (ECG) components were observed. Conclusions: The administration of the C. aronia syn. Azarolus extract induced bradyarrhythmia and hypotension, without alteration in the ECG components.