[Cerebral vasospasm: comparison of contractile responses in isolated human and canine basilar arteries]

Differences between human and canine basilar arteries in contractile responses to various agents were studied in vitro. Human basilar arteries were obtained at postmortem. Serotonin or prostaglandin F2 alpha contracted greatly both human and canine basilar arteries. There was no difference between the two vessels in serotonin- or prostaglandin F2 alpha-induced contractions. In contrast, great differences were found between the two arteries in response to norepinephrine or hemoglobin. Human basilar arteries contracted markedly to norepinephrine while canine basilar arteries did not contract to norepinephrine. This data suggests that sympathetics might play a more important role in the genesis of vasospasm after subarachnoid hemorrhage than has been previously thought. Hemoglobin did not elicit a contraction in human basilar arteries whereas it produced marked contractions in canine basilar arteries. This result indicates that possible participation of hemoglobin as a causative agent in vasospasm could be ruled out. In view of these differences between human and canine cerebral arteries, the canine seems unsuitable for an experimental model of cerebral vasospasm.