Altered extracranial vascular reactivity in patients with cerebral arterial aneurysm: an in vitro study.

Isolated human superficial temporal arteries were constricted by the addition of potassium, norepinephrine, and 5-hydroxytryptamine. Different responses occurred when the vessels were taken from patients with ruptured intracranial aneurysm and from patients without cerebral aneurysm. In the aneurysm group, significantly stronger contractions were demonstrated upon exposure to potassium and 5-hydroxytryptamine. Because these agents increase the movement of extracellular calcium into smooth muscle cells in the excitation-contraction coupling process, it is suggested that, in vessels from aneurysm patients, there is enhanced influx of calcium across the cell membrane and that cerebral vasospasm is thus not due to extravascular actions alone.