Absence of Vasomotor Responses to Epinephrine and Arterenol in an Isolated Intracranial Circulation

Four experimental procedures were tried with the dog before one was found which enabled us to record vasomotor changes in an intracranial vascular bed, uncomplicated by alteration in vasomotor tone in the extracranial beds. This required extensive dissection and cannulation technics. In experiments in which this was accomplished by complete elimination, on one side, of the communications between the internal carotid artery and the various extracranial arteries, it was demonstrated that doses of epinephrine and arterenol, which have marked vasomotor activity on all other vascular beds, are without effect on the intracranial bed supplied by the internal carotid artery.