Central machanisms involved l~l anti-arrhythmic action of vanilol

After the right stellate ganglion of anesthetized rabbits was excised electrical stimulation of the posterior hy-pothalamus consistently resulted in an ar-thythmia with hypertension and mydria-sis. The arrhythmia was prevented by iv vanilol (1- ( 2-methoxy-4-methoxycarbon-yl-l-phenoxy) -3-isopropylamino-2-pro-panol) 10 mg/kg, aminosteroid 5.0 mg/kg, cyclovirobuxine D (CV.B) 2.0 mg/kg. di-phenylhydantoin (DPH) 30 mg/kg or in-travertebrally (ia) DPH 3 mg/kg. Vanilol J mg/kg ia prevcnted the arr-hythmia in 15/18 0f the rabbits (8326), but ia amino-steroid, CVB and propranolol did not. These results suggest that the antiarrhy-thmic action of vanilol against central neurogenic arrhythmia is within the CNS besides its direct action on the heart.