Coronary ligation-reperfusion arrhythmia models in anesthetized rats and isolated perfused rat hearts concentration-effect relationships of lidocaine.

A comparative study of two arrhythmia models was carried out using coronary ligation and reperfusion in anesthetized rats and in isolated rat hearts. Both models allowed evaluation of the concentration-effect relationships of lidocaine as an antiarrhythmic agent. The average free plasma-water concentration that reduced the incidence of ventricular fibrillation by 50% was comparable in both models: 1.9 mg/liter in vivo and 2.1 mg/liter in vitro, respectively. In isolated rat hearts significantly higher concentrations were required for 50% reduction of ventricular tachycardia than for the suppression of ventricular fibrillation (2.9 +/- 0.13 versus 2.1 +/- 0.11 mg/liter, p less than 0.05). The good agreement between effective lidocaine concentrations in vivo and in vitro suggests that the isolated rat heart preparation is suitable for the quantitative assessment of drug effects on occlusion-reperfusion arrhythmias. A better reproducibility and easier control of drug concentrations are the advantages of the in vitro model.