Mechanical properties of human cerebral arteries. Part 1: Effects of age and vascular smooth muscle activation.

Mechanical properties of the smooth muscle component of human arteries were studied under passive and active conditions. There exists a considerable difference in the development of sclorosis in intracranial and extracranial arteries. Intracranial arteries were already stiff at birth and become stiffer with age. Their increase in stiffness is attributable to the marked thickening of their walls, which compensates for the decrease of their elasticity with age. Intracranial arteries constrict more than extracranial arteries, although the maximum active stress developed is essentially the same. This competency of intracranial arteries for vaso-constriction may be related to cerebral vasospasm.