Influence of some hypotensive drugs on the effects of hypothalamic stimulation

Clonidine, L-alpha-methyldopa, propranolol as well as noradrenaline, when injected directly into the hypothalamic paraventricular (PV) nucleus area, enhance the activity of this center. Lidoflazine appears to be inactive. Since the electrical, chemical and pharmacological stimulation of the PV area elicits the same depressor cardiovascular reactions, a specific differentiation of this nucleus as a depressor center is proposed. The above-mentioned drugs, when introduced into the ventromedial nucleus area, enhance the pressor effects produced by stimulation of this nucleus. Thus, the hypothalamic depressor activity is not linked with an inhibition of the ventromedial pressor activity.