Autonomic and Neurohumoral Control of Postprandial Blood Pressure in Healthy Aging

BACKGROUND: Postprandial hypotension (PPH) is a common and morbid problem in elderly people that is associated with an impaired vascular response to meal digestion. Healthy aging in the absence of blood pressure elevation is associated with autonomic and neurohumoral changes that may influence the vascular response to meal ingestion. However, it is not known whether these age-related changes are associated with the development of PPH. METHODS: We measured hemodynamic (blood pressure, heart rate, and forearm vascular resistance), autonomic (power spectral analysis of heart rate and blood pressure variability), and neurohumoral (plasma norepinephrine, renin, aldosterone, and endothelin) responses to a mixed 425 kilocalorie (kcal) meal in 89 rigorously screened healthy subjects aged 20-39, 40-59, and 60-83 years. RESULTS: After the meal, supine mean arterial blood pressure fell significantly only in the middle-aged group by 5.4 +/- 7.9 mm Hg at 30 minutes (p = .02). Forearm vascular resistance fell after the meal in all age groups ( p = .0001). Older groups had higher plasma norepinephrine (p = .02), lower heart rate (p = .03), lower cardiovagal activity (p = .0001), and lower sympathetic vasomotor (p = .000) activity, but there was no difference in the response of these variables to a meal. CONCLUSION: Healthy aging, in the absence of blood pressure elevation, alters the level of autonomic activity without further impairing the ability to maintain blood pressure during meal digestion. Hemodynamic, autonomic, and neurohumoral responses to meal ingestion remain unchanged in very healthy, normotensive elderly adults.