L-Citrulline Attenuates Aortic Pressure And Pressure Waves Amplitude During Metaboreflex Activation In Postmenopausal Women

INTRODUCTION: Postmenopausal women have augmented pressure wave amplitude responses to low-intensity exercise that contributes to increased aortic blood pressure (BP) due to an overactive metaboreflex (postexercise muscle ischemia, PEMI). Moreover, menopause-associated impaired endothelial function attributed to arginine (ARG) and nitric oxide (NO) deficiency may contribute to exaggerated systolic BP (SBP) responses to exercise. L-Citrulline supplementation (CIT) is an ARG and NO precursor that decreases aortic SBP and wave reflection responses to excessive sympathetic activity via cold exposure combined with PEMI in young adults. Furthermore, CIT has shown to reduce pressure wave amplitude responses to cold exposure that resulted in attenuation of aortic SBP in older adults. PURPOSE: To investigate the effects of CIT on aortic BP and amplitude of forward (Pf) and backward (Pb) pressure waves during isometric handgrip (IHG) and metaboreflex activation in healthy postmenopausal women. HYPOTHESIS: CIT would attenuate aortic SBP and amplitude of pressure wave responses to IHG and PEMI. METHODS: Twenty healthy postmenopausal women were randomized to CIT (6 g/day) or placebo (PL) for 4 weeks. Aortic BP, Pf, and Pb responses were assessed via applanation tonometry at rest, during 2 minutes of isometric handgrip (IHG) at 30% of maximal voluntary contraction, and 3 minutes of PEMI. These responses were analyzed as the difference of the change (Δ) from rest to the last minute of IHG and PEMI at 0 and 4 weeks. RESULTS: There were no significant differences between groups in BP and pressure wave amplitudes at rest or in response to IHG and PEMI before supplementation. CIT had no effect on aortic BP or pressure wave amplitude responses from rest to IHG compared to PL. However, CIT attenuated aortic SBP (CIT:Δ-8 ± 3 vs PL:Δ2 ± 2 mmHg; P = .01), aortic mean arterial pressure (CIT:Δ-7 ± 3 vs PL:Δ1 ± 1 mmHg; P = .04), Pf (CIT:Δ-4 ± 1 vs. PL:Δ0 ± 1 mmHg; P = .03), and Pb (CIT:Δ-2 ± 1 vs. PL:Δ0 ± 0 mmHg; P = .01) responses to PEMI compared to PL. CONCLUSIONS: These findings suggest that CIT supplementation effectively decreases aortic SBP during metaboreflex activation due to reductions in amplitude of forward and backward pressure waves in healthy postmenopausal women.