L-Citrulline supplementation attenuates aortic pulse pressure and wave reflection responses to cold stress in older adults.

2022-03
Experimental gerontology 159
- Salvador J Jaime
- Jessica Nagel
- Arun Maharaj
- Stephen M Fischer
- Elizabeth Schwab
- Christopher Martinson
- Kim Radtke
- Richard P Mikat
- Arturo Figueroa

PubMed: 34990772
DOI: 10.1016/j.exger.2021.111685

Study Design

Type: Randomized Controlled Trial (RCT)
Population: 16 older adults
Methods: randomly assigned to placebo or L-CIT (6 g/day) for 14-days in a crossover, double-blind, placebo-controlled design
Blinding: Double-blind
Duration: 14 days
Funding: Unclear

Background and aims

Augmented aortic systolic blood pressure (SBP) and wave reflection via sympathetic-mediated vasoconstriction elevates the risk for adverse cardiovascular events in older adults. L-citrulline (L-CIT) supplementation has shown to reduce aortic SBP and pulse pressure (PP) responses to cold pressor test (CPT) induced sympathoactivation in young men. The aim of this study was to elucidate the efficacy of L-CIT supplementation to attenuate aortic hemodynamic responses to CPT in older adults.

Methods and results

Sixteen older adults were randomly assigned to placebo or L-CIT (6 g/day) for 14-days in a crossover, double-blind, placebo-controlled design. Brachial SBP and aortic SBP, PP, augmented pressure (AP), augmentation index standardized at 75 bpm (AIx@75), and pressure of the forward (Pf) and reflected (Pb) waves were evaluated at rest and during CPT pre- and post-intervention. Although no hemodynamic changes at rest, brachial SBP (Δ-12 ± 18 vs. Δ4 ± 14 mmHg; P = 0.008) and aortic SBP (Δ-10 ± 14 vs. Δ4 ± 12 mmHg; P = 0.005), PP (Δ-10 ± 12 vs. Δ4 ± 11 mmHg; P = 0.002), AP (Δ-4 ± 4 vs. Δ2 ± 7 mmHg; P = 0.004), AIx@75 (Δ-3.2 ± 7.2 vs. Δ2.2 ± 6.9%; P = 0.038), Pf (Δ-6 ± 10 vs. Δ3 ± 9 mmHg; P = 0.019), and Pb (Δ-4 ± 6 vs. Δ2 ± 6 mmHg; P = 0.008) responses to the CPT were significantly attenuated following L-CIT supplementation vs. placebo.

Conclusions

L-CIT supplementation attenuated aortic pulsatile pressure and pressure wave reflection responses to CPT in older adults, providing possible cardioprotection during cold-induced sympathoactivation in older adults.

Research Insights

L-Citrulline→Reduced Aortic Pulse Pressure
Although no hemodynamic changes at rest
Effect
Neutral
Effect size
Small
Dose
6 g/day
L-Citrulline→Reduced Aortic Systolic Blood Pressure
aortic SBP (Δ-10 ± 14 vs. Δ4 ± 12 mmHg; P = 0.005) ... responses to the CPT were significantly attenuated following L-CIT supplementation vs. placebo.
Effect
Beneficial
Effect size
Large
Dose
6 g/day
L-Citrulline→Reduced Augmentation Index
AIx@75 (Δ-3.2 ± 7.2 vs. Δ2.2 ± 6.9%; P = 0.038) ... responses to the CPT were significantly attenuated following L-CIT supplementation vs. placebo.
Effect
Beneficial
Effect size
Small
Dose
6 g/day
L-Citrulline→Reduced Augmentation Index at 75 bpm
AIx@75 (Δ-3.2 ± 7.2 vs. Δ2.2 ± 6.9%; P = 0.038)
Effect
Beneficial
Effect size
Small
Dose
6 g/day
L-Citrulline→Reduced Augmented Pressure
AP (Δ-4 ± 4 vs. Δ2 ± 7 mmHg; P = 0.004) ... responses to the CPT were significantly attenuated following L-CIT supplementation vs. placebo.
Effect
Beneficial
Effect size
Moderate
Dose
6 g/day
L-Citrulline→Reduced Backward Wave Pressure
Pb (Δ-4 ± 6 vs. Δ2 ± 6 mmHg; P = 0.008)
Effect
Beneficial
Effect size
Small
Dose
6 g/day
L-Citrulline→Reduced Diastolic Blood Pressure
Pb (Δ-4 ± 6 vs. Δ2 ± 6 mmHg; P = 0.008) ... responses to the CPT were significantly attenuated following L-CIT supplementation vs. placebo.
Effect
Beneficial
Effect size
Small
Dose
6 g/day
L-Citrulline→Reduced Forward Wave Pressure
Pf (Δ-6 ± 10 vs. Δ3 ± 9 mmHg; P = 0.019) ... responses to the CPT were significantly attenuated following L-CIT supplementation vs. placebo.
Effect
Beneficial
Effect size
Small
Dose
6 g/day