Comparison between the ventricular fibrillation thresholds of spontaneously hypertensive and normotensive rats--investigation of antidysrhythmic drugs.

Induction of ventricular fibrillation by intraventricular electric pulses is achieved with weaker currents in spontaneously hypertensive rats (SHR) than in normotensive rats of the Wistar-Kyoto (WKY) or Sprague-Dawley (SD) strains. The ventricular fibrillation threshold (VFT) is stable with time in SHR but not in WKY. Investigation of antidysrhythmic agents in SHR showed that most substances with membrane-stabilizing properties increase the VFT. There was no correlation between the elevation of VFT and the decrease in heart rate induced by the substances studied. Determination of the VFT in SHR may be useful for the screening of compounds with membrane-stabilizing properties.