EFFECT OF SYMPATHECTOMY AND ADRENALECTOMY UPON GANGLION BLOCKADE

¹ Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston, Texas

Hilton and Steinberg have reported that chlorisondamine does not completely block the pressor response to increased intracranial pressure (IIP) and that addition of atropine or valethamate will block the remaining response. Utilizing the major vessel occlusion technique, studies were performed on dogs to compare the effects of sympathectomy and of adrenalectomy with complete ganglionic blockade. There were no significant differences between the blood pressures after sympathectomy produced either by surgical removal of the ganglia from T₁ to L₂ or by the administration of the combination of chlorisondamine (1 mg/kg) and atropine (1 mg/kg). The pressor response in the caudad zone invoked by IIP was small but significant after sympathectomy. It was further shown that the effects of adrenalectomy are seen in the cephalad zone of the dog and not in the caudad zone. From the results of this study it has been concluded that the actions of chlorisondamine and atropine in blocking the pressor effects of IIP are on or through the sympathetic ganglia.