A new model of ventricular fibrillation induced by isoprenaline and catechol-O-methyl transferase inhibitor at a high perfusion temperature in isolated rat hearts.

Isolated rat hearts were perfused with various concentrations of isoprenaline (0.01-10 mumol/liter) for 30 min at a constant flow rate (6.5 ml/min) at 37-44 degrees C. The occurrence of ventricular fibrillations was isoprenaline concentration dependent and also perfusion temperature dependent in the combined treatment with various concentrations of isoprenaline and high perfusion temperatures. When the hearts were perfused with isoprenaline (1 mumol/liter) in the presence of tropolone (100 mumol/liter) at 40-41 degrees C, the duration of ventricular fibrillations was significantly prolonged, but the incidence of ventricular fibrillations was similar to that produced with isoprenaline (1 mumol/liter) alone. The antiarrhythmic drugs such as quinidine sulfate, lidocaine hydrochloride, dl-propranolol hydrochloride, carteolol hydrochloride, atenolol, dl-verapamil hydrochloride, and diltiazem hydrochloride, given at a concentration of 10 mumol/liter, significantly suppressed the incidence and duration of such ventricular fibrillations. Bretylium tosylate (10 mumol/liter) significantly suppressed the duration of the ventricular fibrillations but not their incidence. These results indicate that ventricular fibrillation induced by combined treatment with a high concentration of isoprenaline and tropolone at a high perfusion temperature in isolated rat hearts is a more useful experimental model of arrhythmia than conventional models.