Structure and reactivity of small arteries in aging.

Abstract

Increased pulse pressure has been observed in aging subjects, but the impact on the structure and reactivity of small arteries has been scarcely evaluated. This study presents the modifications of vascular structure and function observed in female rats of 5, 18 and 32 months of age, and their relation to the prevailing hemodynamic status. Geometry and reactivity of perfused and pressurized basilar and mesenteric small arteries were analyzed in vitro using a video dimension analyzer. Mean arterial pressure was similar in the three age groups, and only pulse pressure was increased in the oldest group. Media thickness and cross sectional area increased in basilar and mesenteric arteries of the oldest rats and these structural abnormalities were positively related to pulse pressure but not to mean, systolic or diastolic arterial pressure. Only minor changes of vascular reactivity were noted with age: there was a decreased contraction to angiotensin II in mesenteric arteries and an enhanced contraction to endothelin-1 in the basilar arteries. In conclusion, aging is associated with increased pulse pressure and hypertrophy of basilar and mesenteric resistance arteries, suggesting that this hemodynamic variable may influence cerebral and peripheral vascular structure in aging.