L-Citrulline Supplementation Attenuates Cardiovascular Responses to Metaboreflex Activation with Cold Exposure in Young Overweight Men

Abstract

Cold-induced increases in left ventricular afterload may increase the risk for cardiac events in individuals with high cardiovascular risk. Obese individuals have higher blood pressure (BP) and sympathetic responses to post-exercise muscle ischemia (PEMI) than lean counterparts. L-citrulline supplementation attenuates systolic BP (SBP) and pressure wave reflection (augmentation index, AIx) responses to the cold pressor test (CPT), but the capacity of L-citrulline to reduce aortic hemodynamics and arterial stiffness responses during PEMI with and without cold exposure is unknown. PURPOSE: To examine if L-citrulline supplementation would attenuate hemodynamic responses to PEMI with and without CPT (PEMI+CPT). METHODS: Fourteen healthy overweight/obese men (age 24 ± 6 y; BMI 29.3 ± 4.0 kg/m2) were randomly assigned to placebo (maltodextrin) or L-citrulline (6 g/day) supplementation for 14 days and cross-over after 14 days of wash-out. Brachial SBP, aortic SBP, aortic AIx, brachial-ankle pulse wave velocity (baPWV, a marker of arterial stiffness), and heart rate were evaluated at baseline, during PEMI, and during PEMI+CPT. RESULTS: During PEMI, L-citrulline significantly decreased aortic AIx (-8.6 ± 2.0%; P < 0.01) compared with placebo, but did not affect brachial SBP, aortic SBP, and baPWV. During PEMI+CPT, L-citrulline decreased brachial SBP (-11 ± 3 mmHg, P < 0.01), aortic SBP (-13 ± 3 mmHg, P < 0.01), aortic AIx (-13.8 ± 2.2%, P < 0.01), and baPWV (-0.9 ± 0.4 m/s, P < 0.05) compared with placebo. CONCLUSIONS: L-citrulline supplementation attenuated the increases in peripheral and central SBP, wave reflection, and arterial stiffness during metaboreflex activation in the cold, a condition with greater vascular responses than PEMI without CPT.