P561Acute effects of dronedarone and amiodarone on functional, morphological and oxidative stress parameters in isolated rat heart with hypertension

Introduction Amiodarone represents the most widely used antiarrhythmic drug, even though it has been shown that it has negative inotropic and lusitropic effect in healthy hears. On the other hand, dronedarone reduces the risk of recurrent atrial fibrillation, but with increased early mortality related to the worsening of heart failure. However, the mechanisms responsible for these fatal outcomes remain unclear and require further examinations. Purpose To investigate acute, direct effects of Dronedarone and Amiodarone on cardiac contractility, coronary flow and oxidative stress parameters in isolated rat heart with hypertension. Methods The present study was carried out on 18 isolated hearts of spontaneously hypertensive Wistar Kyoto male rats (6 weeks old, bodyweight 200 ± 10 g). After isolation, all hearts were retrogradely perfused according to Langendorff technique with a gradually increment of coronary perfusion pressure (CPP from 40 to 120 cm H2O) and randomly divided into 3 groups: Control (n = 6), Amiodarone (n = 6, isolated hearts perfused with Amiodarone in dose of 3 umol), Dronedarone (n = 6, isolated hearts perfused with Dronedarone in dose of 1.8 umol). During ex vivo protocol continuously were registered cardiac contractility parameters and coronary flow, while from collected coronary venous effluent markers of oxidative stress were measured. All hearts were then fixated and stained with Hematoxylin/eosin. Results Dronedarone severely depressed the function of all cardiodynamic parameters of the heart compared with Amiodarone or Control while Amiodarone intensified the function of the isolated rat heart with hypertension compared to Control (dp/dt max mmHg/s at coronary perfusion pressure 120cmH2O Dronedarone vs. Amiodarone vs. Control 579.733 ± 202.27 vs. 3063.65 ± 467.93 vs. 2682.88 ± 368.75; p < 0.001. dp/dt min mmHg/s 120cmH2O -352.13 ± 204.65 vs. 1960 ± 242.21 vs. -1858.83 ± 118.23; p < 0.001. SLVP mmHg at CPP 120cmH20 27.8 ± 3.46 vs. 98.95 ± 11.78 vs. 71.45 ± 7.56; p < 0.001. DLVP mmHg at CPP 120cmH2O 6.32 ± 0.49 vs. 4.83 ± 0.54 vs. 0.85 ± 0.35; p < 0.001). Acute administration of Dronedarone decreased the level of NO2- and increased the level of H2O2 , while Amiodarone heightens O2- levels (O2- nmol/min g wt at coronary perfusion pressure 120cmH2O Dronedarone vs. Amiodarone vs. Control 28.62 ± 2.54 vs. 77.3 ± 8.86 vs. 31.72 ± 4.56; p < 0.001. H2O2 nmol/min g wt at CPP 120cmH2O 92.56 ± 11.65 vs. 48.63 ± 10.11 vs. 42.84 ± 84; p < 0.001. NO2- nmol/min g wt at CPP 120cmH2O 38.61 ± 4.94 vs. 82.28 ± 5.76 vs. 64.71 ± 3.51; p < 0.001). Pathohistological, structural changes were observed in both, experimental groups. Conclusions Acute administration of Dronedarone depresses cardiac function in isolated, working rat heart with hypertension, with decreasing the NO2- levels, increasing the level of H2O2 and enhanced structural changes when compared to Amiodarone.