L-citrulline Supplementation Attenuates Aortic Pressure And Wave Reflection Responses To Cold Stress In Older Adults

Abstract

PURPOSE: Aging is a major risk factor for cardiovascular events due to increased pressure wave reflection. Cold exposure augments central blood pressure and wave reflection due to sympathetic-mediated vasoconstriction, which elevates the risk for adverse cardiovascular events in older adults. L-citrulline (L-CIT) supplementation improves endogenous synthesis of nitric oxide and contributes to reduce aortic systolic blood pressure (SBP) and pulse pressure (PP) responses to cold pressor test (CPT) in young men; however, the impact on wave reflection in older adults is unknown. The purpose of this study was to elucidate the efficacy of L-CIT to attenuate aortic hemodynamic responses to CPT in older adults. METHODS: Sixteen adults (n=16, 60-85 yrs) were randomly assigned to placebo or L-CIT (6g/day) for 14 days in a crossover, double-blind design. Brachial and aortic SBP, PP, augmented pressure (AP), augmentation index standardized at 75 bpm ([email protected]), and pressure of the forward (Pf) and reflected (Pb) waves were evaluated at rest and during CPT before and after the assigned intervention. An analysis of variance with repeated measures was used to determine if there were differences within and between interventions at rest and during CPT. RESULTS: No significant changes with either intervention were observed at rest. Responses in aortic PP (-9.1 vs. 2.9; P=.008), AP (-4.1 vs. 2.1; P=.004), AIx (-3.7 vs. 2.1; P = .015), [email protected] (-3.4 vs. 2.4; P = .024), Pf (-5.1 vs. 2.9; P = .034), and Pb (-3.4 vs. 1.7; P = .027) were significantly attenuated following L-CIT supplementation compared with placebo. CONCLUSIONS: Although L-CIT had no effect on resting aortic hemodynamics, L-CIT attenuated aortic pressure and wave reflection responses during CPT in older adults. Therefore, short-term L-CIT supplementation may elicit cardioprotection during cold exposure in older adults.