Acute Citrulline Blunts Aortic Systolic Pressure during Exercise and Sympathoactivation in Hypertensive Postmenopausal Women

Abstract

PurposeHypertensive postmenopausal women (PMW) have exaggerated exercise systolic blood pressure (SBP) due to impaired functional sympatholysis. l-Citrulline (CIT) supplementation attenuates aortic SBP responses to cold pressor test (CPT)–induced vasoconstriction in young men. We hypothesized that acute CIT ingestion would attenuate aortic SBP and leg hemodynamic responses during exercise and CPT (EX + CPT).MethodsFifteen hypertensive PMW (61 ± 7 yr) were randomly assigned to consume either 6 g of CIT or placebo (PL) separated by a minimum 3-d washout phase. Brachial and aortic blood pressure, femoral artery blood flow (FBF), and vascular conductance (FVC) were measured at rest and during 5 min of unilateral plantarflexion exercise with a CPT applied during minutes 4 and 5.ResultsNo differences between conditions were found in FBF, FVC, and brachial and aortic blood pressure at rest and during exercise alone. Changes in brachial SBP (CIT vs PL, 29 ± 12 vs 40 ± 10 mm Hg) and mean arterial pressure (CIT vs PL, 21 ± 10 vs 33 ± 11 mm Hg), and aortic SBP (CIT vs PL, 27 ± 11 vs 38 ± 9 mm Hg) and mean arterial pressure (CIT vs PL, 23 ± 9 vs 33 ± 11 mm Hg) to EX + CPT were lower in the CIT versus PL condition (P < 0.05). FBF, FVC, and functional sympatholysis (%ΔFVC) were not significantly different between conditions.ConclusionsAcute CIT ingestion attenuated aortic SBP response to exercise and cold-induced sympathetic activation that may prevent left ventricle overload in hypertensive PMW.

Effects of L-Citrulline Supplementation on Endothelial Function and Blood Pressure in Hypertensive Postmenopausal Women

“…Conversely, acute ingestion of 10 g of L-CIT, the maximal clinically effective dose, did not improve microvascular reactive hyperemic blood flow in healthy older men [ 53 ] and older adults with heart failure [ 54 ]. Moreover, we found that an acute 6 g dose of L-CIT was unable to improve superficial femoral artery blood flow or vascular conductance during low-intensity exercise [ 55 ]. These previous findings suggest that L-CIT may need to be supplemented for at least 4 weeks to observe significant benefits in endothelial function.…”

L-Citrulline supplementation attenuates aortic pressure and pressure waves during metaboreflex activation in postmenopausal women

“…Notably, CIT did not reduce wave reflection during PEMI without cold exposure, indicating that CIT is less efficient to attenuate haemodynamic responses to mild sympathetic-mediated vasoconstriction in healthy young men (23) . Thus, CIT may be more efficacious in populations with exaggerated BP and sympathetic responses to exercise and cold exposure, such as hypertensive postmenopausal women and older adults (17,22) . The efficiency of CIT to attenuate Pf and Pb responses to cold-induced sympathetic vasoconstriction was previously demonstrated after 2 weeks of supplementation in older adults (22) .…”

“…Moreover, evidence indicates that CIT can reduce aortic SBP, PP, and pressure wave amplitude responses to sympathetic overactivation induced via cold exposure in older adults (22) . Similarly, acute L-citrulline (6 g) and chronic CIT (6 g/d) attenuated aortic SBP responses to exercise and to PEMI combined with cold exposure in hypertensive postmenopausal women (17) and healthy young men (23) , demonstrating the ability of CIT to effectively control BP responses to conditions with excessive sympathetic activity. However, a single dose of CIT had no BP lowering effect during dynamic exercise without cold exposure in postmenopausal women (17) , suggesting that a higher dose may be necessary to reduce exercise BP.…”

“…Increasing NO bioavailability via ARG precursors may be an effective approach to improve vasodilatory capacity and reduce exercise hypertension in postmenopausal women (17) . Evidence indicates oral L-citrulline supplementation (CIT) is more efficient at increasing circulating ARG levels than a similar dose of ARG (18) , resulting in greater NO bioavailability (19) .…”