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Adding arginine to an essential amino acid (EAA) feed reverses age‐related impairments in vascular responsiveness
Author(s) -
Mitchell William Kyle,
Williams John,
Rankin Debbie,
Lund Jonathan,
Larvin Mike,
Phillips Bethan,
Smith Kenneth,
Atherton Philip J
Publication year - 2013
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.27.1_supplement.679.5
Subject(s) - medicine , arginine , nitric oxide , blood flow , microbubbles , endocrinology , perfusion , vascular smooth muscle , cardiology , ultrasound , chemistry , amino acid , biochemistry , smooth muscle , radiology
Impaired vascular function in older age compromises the positive effects of nutrition on limb blood flow, perhaps impacting on maintenance of healthy muscle mass. Herein, we explored: (i) the effect of age upon macro/ micro‐vascular limb blood flow responses to nutrition, and (ii) the potential for arginine, the substrate of nitric oxide synthase, to improve nutrient‐mediate vascular responsiveness in older people. Using contrast enhanced ultrasound (CEUS) with Sonovue™ sulfur hexafluoride microbubbles, along with phase shift Doppler, we measured: changes in leg blood flow (LBF), quadriceps muscle microvascular perfusion (MMP) and microvascular flow velocity (MFV) in response to a 15g oral mixed EAA feeding in 8 young (~20y) and 8 older (~70y) men. An additional 8 older men (~70y) had the same 15g mixed EAA feed, supplemented with 3g L‐arginine. Young men showed marked vascular responses to EAA: LBF increased 44±11% ( P <0.001), MFV increased 78±31% ( P <0.01) and MMP increased 130±52% ( P <0.001) from fasting. In contrast, older men fed 15g EAA had no significant changes in LBF or indices of muscle microvascular flow, while older men receiving 15g EAA with 3g arginine displayed increases in LBF (25±5%, P <0.05), MFV (88±48%, P <0.001) and MMP (110±70%, P <0.05, all 2‐way RM ANOVA). We conclude that supplementing EAA with L‐arginine restores some of the macro/ micro‐vascular responsiveness to feeding lost with aging.