Functional and metabolic effects of propafenone in the rat heart-lung preparation.

The effects of propafenone on cardiac function and myocardial metabolism were assessed in the isolated rat heart-lung preparation. Propafenone 0.3, 3 or 30 microg.ml(-1) was administered 5 min after the start of perfusion. Heart rate decreased in the 30 microg.ml(-1) group significantly following the drug administration. The highest dose of propafenone (30 microg.ml(-1)) reduced cardiac output significantly, and this dose was associated with a higher incidence of arrhythmias than the other groups. Although there were no significant differences in myocardial lactate and glycogen concentrations among groups, ATP content in the 30 microg.ml(-1) group was significantly less than that in the control group. As therapeutic plasma concentration of propafenone is about 0.6 (range 0.06 to 1.0) microg.ml(-1), 30 microg.ml(-1) is 50 times greater than its concentration. These results suggest that the negative inotropic and chronotropic effects of propafenone are almost same with those of lidocaine which we have previously reported.