Reduction in vulnerability to ventricular fibrillation by bromocriptine, a dopamine agonist.

The effect of a dopamine agonist, bromocriptine, on ventricular fibrillation (VF) threshold was studied in anaesthetised dogs. Bromocriptine produced an increase of 50% in VFT. Pretreatment with the dopamine antagonist haloperidol abolished the effects of bromocriptine on VF threshold as did pretreatment with the peripheral dopamine antagonist, domperidone. It is concluded that bromocriptine reduces vulnerability of the nonischaemic canine ventricle to fibrillation. This effect is most probably mediated by peripheral presynaptic stimulation of dopaminergic receptors, thereby inhibiting noradrenaline release.