Inhibitory effects of gamma-aminobutyric acid and diazepam on ventricular arrhythmias induced by hypothalamic electric stimulation

The experiments were carried out on rabbits with ventricular arrhythmias (VA) induced by hypothalamic electric stimulation. The effects of GABA or diazepam (Dz) and picrotoxin on VA were observed. After GABA 0.25, 0.5, 1 mg/rabbit were injected into cerebral ventricle (icv) or cisterna magna (icm), the VA was dose-dependently reduced, the similar effect was seen after Dz 0.1 mg was injected into subarachnoid cavity (sac) or icm. The effect was not induced by GABA sac or Dz icv. Picrotoxin 20 micrograms icv or 30 micrograms icm obviously increased VA, and this effect was partly antagonized by pretreatment with GABA 0.5 mg icv or icm and Dz 0.1 mg icm. The results suggest that central GABAergic system plays an important role in development of arrhythmias, and that increasing activity in this system may inhibit VA.