No toxic effects and no spontaneous arrhythmias were recorded because all preparations remained in a stable condition throughout the experiment.
At the end of the experiments ventricles treated with DPI 201-106 plus veratridine responded to electrical stimulation with torsade de pointes-like episodes (Figure 3). This observation should be taken as a preliminary indication for the sensitivity of the model for torsade de pointes induction.
The aim of the present experiments was to create the conditions for the genesis of torsades de pointes arrhythmias in guinea-pig isolated hearts. Because torsades de pointes are a ventricular form of arrhythmia, the atria together with the sinus node were surgically removed in order to work with solely ventricular preparations beating in AV rhythm. By comparing Langendorff-perfused whole hearts beating in sinus rhythm with ventricular preparations beating in AV rhythm, we have shown in our experiments that both are sufficiently stable with respect to QTc during the experimental time of about 2 h. The small decrease over time in heart rate and contractility also remained in the same order of magnitude in both preparations. Thus, we used ventricular preparations without atria and beating spontaneously in slow AV rhythm for further experiments. You will always enjoy getting proventil albuterol, being 100% sure you are safe.
Figure 3 Torsade de pointes-like arrhythmia induced by single pulse electrical stimulation (arrow) in Langendorff-perfused guinea-pig ventricles treated with DPI 201-106 plus veratridine, each 0.5 цМ