Evaluation of the effect of dopamine and other catecholamines on the electrocardiogram and blood pressure of rats by means of on-line biosignal processing.

We compared the effects of dopamine and other catecholamines under identical conditions on electrocardiograms (ECG), heart rate, and blood pressure of rats. The experiments were carried out on anesthetized male Wistar rats weighting 330-370 g. The ECG was taken by a bipolar ECG lead in the direction of the heart axis, mean arterial pressure was measured in the carotid artery. Dopamine, adrenaline, noradrenaline, isoproterenol, and isotonic saline (control) were administered by continuous intravenous infusion. The infusion rate was increased 10-fold every 10 min starting with therapeutic dosages. All data were evaluated by continuous on-line biosignal processing. The results confirmed the well-known cardiovascular effects of the catecholamines; heart rate and mean arterial pressure increased after all adrenergic drugs except for isoproterenol, which caused a fall in pressure. In the ECG the PRc interval was significantly increased only by the highest doses of adrenaline and noradrenaline. A widening of the QRS complex was not observed during dopamine infusion, whereas it was present during adrenaline, noradrenaline, and especially, isoproterenol infusions. Taking the widening of QRS as indicative of cardiotoxic drug effects, the tested catecholamines may be arranged in the following order of cardiotoxicity; dopamine > adrenaline congruent to noradrenaline < isoproterenol.