Digitalis: neurally mediated arrhythmogenic and coronary vasoconstrictor properties.

Studies of digitalis have revealed an appreciable role of the autonomic nervous system in the modulation of the cardiovascular toxicity of digitalis. Neuraxis transection experiments and studies using digitalis compounds that fail to enter the central nervous system suggest that centers located in the floor of the fourth cerebral ventricle play a substantial part in the neural arrhythmogenic effects of the digitalis glycosides. Electrical stimulation of the area postrema in partially digitalized animals, not otherwise manifesting ventricular arrhythmias, elicits ventricular tachycardia. Neuraxis transection experiments and studies with a charged digitalis derivative also suggest localization of the coronary vasoconstrictive properties of digitalis to the area postrema. The results suggest that this region of the brainstem is sensitive to a neurally active substance, digitalis, causing peripheral sympathetic effects of considerable consequence.