Influence of neural regulation on anti-arrhythmic effects of GABA in rats

In anesthetized rats, GABA 10 mg.kg-1 iv delayed the onset of ventricular premature (VP) (P less than 0.01) and ventricular tachycardia (VT) (P less than 0.01) and reduced the incidence of ventricular fibrillation (VF) (P less than 0.05). The anti-arrhythmic effects of GABA remained after cervical vagotomy, iv hexamethonium 10 mg.kg-1 or destruction of CNS. It was also seen on pithed rats. In Langendorff heart, GABA 100 mg.L-1 elevated the threshold doses of aconitine required to induce VT (P less than 0.01), VF (P less than 0.01), and heart stop (HS) (P less than 0.01). These results suggest that iv GABA counteracts aconitine-induced arrhythmia directly on the heart, not related to the neural regulation.