Impact Of Age On Aortic Pressure And Pressure Waves Responses To Metaboreflex Activation In Women

Abstract

INTRODUCTION: Aging and hypertension are related to exaggerated peripheral blood pressure (BP) responses to exercise and metaboreflex activation (post-exercise muscle ischemia, PEMI). Postmenopausal (POST) women have greater risk of heart failure with preserved ejection fraction due to increased aortic pulsatile load on the left ventricle induced by increased systolic BP (SBP) and decreased diastolic BP (DBP) at rest. Age-related aortic stiffening augments pressures of the forward (Pf) and the reflected wave (Pb) traveling from peripheral arteries to the aorta. Increases in Pf and Pb contribute to elevated aortic SBP and pulse pressure (PP) responses to exercise, increasing the risk for cardiovascular events. However, the influence of Pf and Pb on aortic pulsatile load during isometric handgrip (IHG) and PEMI in normotensive premenopausal (PRE) and POST women have not been examined. PURPOSE: To investigate the effect of age on aortic BP, Pf, and Pb during IHG and PEMI in normotensive PRE and POST women. METHODS: Fifteen PRE (age: 24 ± 1 years) and 16 POST women (age: 59 ± 1 years) participated in this study. Brachial BP was obtained using an automated device and radial arterial tonometry was used to capture aortic waveforms to estimate aortic BP and pressure waves at rest, during a 2-min IHG at 30% of maximal force, and during a 3-min PEMI. RESULTS: BP responses to IHG were similar in both groups. Brachial PP (POST: Δ9 ± 1 mmHg vs PRE: Δ0 ± 2 mmHg, P < 0.01), aortic PP (POST: Δ8 ± 1 mmHg vs PRE: Δ3 ± 2 mmHg, P = 0.03), Pf (POST: Δ6 ± 1 mmHg vs PRE: Δ0 ± 1 mmHg, P < 0.01), and Pb (POST: Δ5 ± 1 mmHg vs PRE: Δ2 ± 1 mmHg, P = 0.02) responses to PEMI were significantly increased in POST compared to PRE women. Aortic DBP (POST: Δ6 ± 1 mmHg vs PRE: Δ11 ± 2 mmHg, P = 0.04) responses to PEMI was significantly lower in POST than PRE women. Brachial and aortic SBP significantly (P < 0.001) increased during PEMI in both PRE and POST women, but there was no difference (P > 0.05) between groups. CONCLUSION: Normotensive POST women have augmented aortic PP response to PEMI compared to PRE women due to increases in pressure of the forward and backward waves and a decrease in DBP. Our findings suggest that the age-related increase in muscle metaboreflex activation does not induce a systolic overload and the increase in aortic PP is attributed to reduced DBP in normotensive POST women.