THE EFFECT OF DRUGS INJECTED INTO LIMITED PORTIONS OF THE CEREBRAL CIRCULATION

¹ Department of Pharmacology, University of Wisconsin Medical School, Madison

By ligation of the basilar artery, the circulation of the internal carotid and vertebral arteries was separated allowing the administration of drugs to centers of the brain above or below the level of ligation.

Picrotoxin, pentylenetetrazol, and nikethamide caused convulsant activity when introduced into the brain either above or below the midpontine level; however, the sensitivity of the lower centers to pentylenetetrazol was much reduced.

Convulsions occurred as a result of the administration of cocaine hydrochloride by way of the internal carotid artery; whereas, this agent caused severe depression of the medullary centers when injected into the vertebral artery.

Thiopental sodium produced respiratory arrest when introduced into the medullary and lower pontine portions of the central nervous system. Much higher concentrations of the drug administered into the higher centers of the brain caused no significant respiratory depression when the vagi were intact.

After section of the vagi, injection of thiopental into the internal carotid artery produced respiratory depression accompanied by an apneustic pattern of respiratory activity.