The Effects of Infra-Arterial Histamine on Blood Flow in the Internal and External Carotid Artery of Man

Both internal and external carotid artery phasic blood flow and arterial pressure were measured in five patients during a control period and after the intra-arterial injection of 13.8 μg of histamine phosphate into each vessel. In the internal carotid artery, flow for the group increased almost immediately and reached a maximum value of 59% greater than control in ten seconds. The total duration of the response in both pressure and flow lasted approximately one minute. The injection of histamine into the external carotid artery elicited a much more marked response, having a maximum increase in flow of 294% for the group with a total duration of the response lasting two and one-half to three minutes. These data define the magnitude and time course of the action of histamine phosphate on the intracranial and extracranial circulation in man.