Centrally mediated hypotension and bradycardia induced by an aminotetralin derivative: TL-68.

An aminotetralin derivate, N,N-dipropyl-2-amino-1,2,3,4-tetrahydronaphthalene (TL-68) induced a prolonged decrease in blood pressure and heart rate when administered i.v. in anesthetized cats. The compound inhibited the blood pressure and heart rate responses induced by central stump stimulation of the sciatic nerve indicating inhibition of sympathetic transmission. TL-68 caused a weak inhibition of the positive chronotropic response induced by stimulation of the cardioaccelerator nerve. When comparatively low doses of TL-68 were injected into the left vertebral artery, a considerable dose-dependent decrease in blood pressure and heart rate developed. The same doses had only small or negligible effects on blood pressure and heart rate when given intravenously. When TL-68 was injected into a lateral cerebral ventricle of unanesthetized rats, a significant hypotension and bradycardia was observed which could be prevented by prior intraventricular injection of phentolamine. The results suggest that this compound exerts its effect through a central mechanism of action, perhaps by stimulation of alpha-adrenoreceptors.