The Influence of Aging on Central Artery Stiffness and Cerebral Vascular Function Following an Acute Hypertensive Stimulus

Abstract

Aging decreases cerebral blood flow and increases cerebral pulsatility. High‐intensity resistance exercise (RE) has been shown to acutely increase blood pressure (BP) and reduce cerebral blood velocity (CBv), resulting in greater flow pulsatility in the cerebral circulation, potentially injuring cerebral microvasculature. Understanding the relationship between aging and cerebral blood flow regulation in response to a hypertensive physiological stress (e.g. RE), is important due to its association with increased risk of cerebrovascular events in older adults.ObjectiveTo examine the effect of age on cerebral blood flow dynamics following acute RE in young and older adults.MethodsYoung (n=35, 26 yrs, BMI: 23.8 kg/m2) and older (n=26, 60 yrs, BMI: 30.1 kg/m2) adults performed maximal leg‐extension/flexion RE (3×10 rep), with hemodynamic measurements obtained pre and post‐RE (immediate, 5‐, 30‐min). CBv was measured via transcranial Doppler. Central pulse wave velocity (PWV) was acquired by an automated ambulatory BP cuff. Common carotid artery beta‐stiffness index (β) and blood flow pulsatility were measured by ultrasonography. Continuous beat‐to‐beat heart rate (HR), cardiac output (Q), blood pressure (SBP, DBP, MAP, PP) and end‐tidal CO2 were also measured.ResultsMean and diastolic CBv increased immediately post‐RE in the young (interaction, p<0.05) and decreased below baseline at 5‐min post‐RE (p<0.05) in both groups. Older adults had a greater increase in CBv pulsatility immediate post‐RE (interaction, p<0.05) compared to the young, but continued to rise at 5‐min post‐RE only in the young (interaction, p<0.05). MAP was higher and carotid pulsatility was lower in the older group and increased immediate post‐RE (p<0.05) in both groups. PWV increased immediate post‐RE (p<0.05), and remained elevated at 5‐min post‐RE in the young (interaction, p<0.05). There were no changes in β.ConclusionsImmediately following the cessation of the hypertensive stimulus, an increase in aortic arterial stiffness and BP occurred, accompanied by an increase in carotid and cerebral pulsatility. Despite obtaining higher BP during the stimulus in the older group, mean and diastolic CBv did not increase post‐RE, resulting in greater cerebral pulsatility in older adults. This differential age response indicates reduced cerebral hemodynamic responsiveness to an acute increase in BP with aging.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.