Long-term caloric restriction improves baroreflex sensitivity in aging Fischer 344 rats.

The effects of aging and caloric restriction on mean arterial pressure (MAP), heart rate (HR), and baroreflex sensitivity were determined in young (7-9 months) and old (22-24 months) awake, male Fischer 344 rats which had been either ad libitum fed or calorie restricted (60% of the ad libitum calories). The MAP of young rats was higher than that of old rats. The MAP of old ad libitum fed rats was higher than that of old restricted rats with no effect of diet in young rats. The HR of restricted rats was lower than ad libitum fed rats with no significant age effect. Reflex bradycardia to hypertensive episodes was greater in restricted than in ad libitum fed rats. Reflex tachycardia to hypotensive episodes was greater in young than in old rats and greater in calorie restricted than in ad libitum fed rats. These findings demonstrate that caloric restriction alters the age-associated decline in several hemodynamic parameters.