Mechanical properties of human cerebral arteries: Part 2. Vasospasm.

Mechanical properties of human intracranial vertebral arteries subjected to subarachnoid hemorrhage were studied. Their pressure-diameter curves are biphasic and have sharp flexion, called flexion points, at a pressure of 181.3 +/- 9.6 mm. Hg when their smooth muscle is activated by KCl 50 mM. The strong vasoconstriction, accompanied by little change in the vascular diameter, is retained up to the pressure level at the flexion point, above which the constriction is released abruptly. The existence of flexion points at a high pressure level is an important mechanical feature in considering the development and treatment of cerebral ischemia produced by vasospasm.