Vascular remodeling in hypertension.

Cerebral arterioles in stroke-prone spontaneously hypertensive rats (SHRSP) paradoxically become more distensible, despite hypertrophy of the vessel wall. Cerebral arterioles in SHRSP also undergo remodeling with a reduction in external diameter. Based on these findings, we have proposed the concept that remodeling of cerebral arterioles may be an important mechanism, in addition to hypertrophy, for encroachment on the vascular lumen in SHRSP. The purpose of this review is threefold. First, consequences of vascular hypertrophy that have been proposed previously are reviewed with an emphasis on the hypothesis that encroachment on the vascular lumen by hypertrophy is an important mechanism of altered vascular responses in chronic hypertension. Second, the concept of vascular remodeling is considered with an emphasis on the possibility that remodeling with a reduction in external diameter may contribute importantly to altered cerebral vascular responses in SHRSP. Finally, possible mechanisms of vascular remodeling are considered with an emphasis on the hypothesis that a reduction in external diameter may be related to a decrease in the length of individual smooth muscle cells without an increase in cell number, or an increase in the number of times each smooth muscle cell wraps around the arteriole.