Abstract 93: The Potential Mechanisms of Reduced Incidence of VF as the Presenting Rhythm
Background. In our previous studies, we have demonstrated that the administration of both beta-adrenergic receptor blocker (βετα-blocker) and angiotensin converting enzyme (ACE) inhibitor significantly shortened the duration of ventricular fibrillation (VF). In the present study, we investigated the potential mechanisms of shortened VF durations by pre-treatment of βετα-blocker and ACE inhibitor.
Hypothesis. Both βετα-blocker and ACE inhibitor increase the duration of monophasic action potential (MAP) and ventricular fibrillation threshold (VFT) which accounted for the decreased duration of VF.
Methods and Results. Three groups from a total of 15 Sprague-Dawley rats weighing 450 –550 g were fed βετα-blocker propranolol (40 mg/kg/day), ACE inhibitor captopril (100 mg/kg/day), or diluent placebo continuously for 30 days prior to the experiment. MAP90 were measured by self-made contact electrophysiology catheter in an open chest rat model. VFT was determined as the lowest current intensity at which two consecutive stimuli precipitated VF using a previously reported method. Both propranolol and captopril significantly increased the VFT and MAP90 in comparison with placebo controls (Table⇓).
Conclusions. Increased VFT and MAP90 in a rat model pretreated with propranolol and captopril may be the potential mechanisms of reduced duration of VF.