The effects of aging on the functional and structural properties of the rat basilar artery

Aging leads to progressive pathophysiological changes in blood vessels of the brain and periphery. The aim of this study was to evaluate the effects of aging on cerebral vascular function and structure. Basilar arteries were isolated from male Fischer 344 cross Brown Norway (F344xBN) rats at 3, 8, and 24 months of age. The basilar arteries were cannulated in the pressurized system (90 cm H2O). Contractile responses to KCl (30-120 mmol/L) and endothelin-1 (10(-11)-10(-7) mol/L) were evaluated. Responses to acetylcholine (ACh) (10(-10)-10(-4) mol/L), diethylamine (DEA)-NONO-ate (10(-10)-10(-4) mol/L), and papaverin (10(-10)-10(-4) mol/L) were assessed to determine both endothelium-dependent and endothelium-independent responsiveness. Advanced aging (24 months) decreased responses of the basilar artery to both the contractile and relaxing agents; whereas, DEA-induced dilation was significantly higher in the 8-month-old group compared with the younger and older groups. The arterial wall-to-lumen ratio was significantly increased in 24-month-old rats. Smooth muscle cell count was also decreased in old rats. These findings indicate that aging produces dysfunction of both the endothelium and the vascular smooth muscle in the basilar artery. Aging also alters wall structure of the basilar artery, possibly through decreases in smooth muscle cell number and concomitant hypertrophy.