A placebo controlled evaluation of the antifibrillatory effects of carvedilol.

This article evaluates the antifibrillatory effects of carvedilol 5 mg/kg and vehicle (dimethyl-formamide) over time. Sprague-Dawley rats were anesthetized and intubated. They underwent baseline ventricular fibrillation threshold (VFT) determination and then received 1 of the 2 treatments (n = 10/group) over 8 minutes. VFT and determinations were performed at 2, 7, 15, 30, 45, and 60 minutes postinfusion. Carvedilol significantly increased the VFT at 2, 7, 15, 30 minutes versus baseline and the vehicle control group. Carvedilol significantly reduced the heart rate and the mean arterial pressure at every evaluable time point versus baseline and vehicle control. Carvedilol showed significant antifibrillatory effects versus baseline and vehicle for the first 30 minutes but not thereafter, even though the heart rate and mean arterial pressure remain significantly reduced.