Exercise-induced brachial artery vasodilation: effects of antioxidants and exercise training in elderly men

Abstract

Aging, vascular function, and exercise are thought to have a common link in oxidative stress. Of the 28 subjects studied (young, 26 +/- 2 yr; old, 71 +/- 6 yr), 12 took part in a study to validate an antioxidant cocktail (AOC: vitamins C, E, and alpha-lipoic acid), while the remaining 8 young and 8 old subjects performed submaximal forearm handgrip exercise with placebo or AOC. Old subjects repeated forearm exercise with placebo or AOC following knee-extensor (KE) exercise training. Brachial arterial diameter and blood velocity (Doppler ultrasound) were measured at rest and during exercise. During handgrip exercise, brachial artery vasodilation in the old subjects was attenuated compared with that in young subjects following placebo (maximum = approximately 3.0 and approximately 6.0%, respectively). In contrast to the previously documented attenuation in exercise-induced brachial artery vasodilation in the young group with AOC, in the old subjects the AOC restored vasodilation (maximum = approximately 7.0%) to match the young. KE training also improved exercise-induced brachial artery vasodilation. However, in the trained state, AOC administration no longer augmented brachial artery vasodilation in the elderly, but rather attenuated it. These data reveal an age-related pro-/antioxidant imbalance that impacts vascular function and show that exercise training is capable of restoring equilibrium such that vascular function is improved and the AOC-mediated reduction in free radicals now negatively impacts brachial artery vasodilation, as seen in the young.

Fig. 1.

α-Phenyl-tert-butylnitrone (PBN) spin adducts assessed by electron paramagnetic resonance (EPR) spectroscopy (top) and concentration of serum lipid hydroperoxides (LH; bottom) under the conditions of rest and after exercise with placebo (PL) and the oral antioxidant (AO) cocktail in young and old subjects (n = 12). Values are means ± SE. Inset at top are representative individual examples of PBN EPR spectra in each scenario. +P < 0.05, significantly different from resting levels. *P < 0.05, significantly different levels during AO trial from levels in matched PL condition.

Fig. 2.

Change in brachial artery diameter (top) and shear rates (bottom) in young and old subjects at rest and at 3 levels of handgrip exercise either after the ingestion of the AO cocktail or placebo. Values for %change in brachial diameter (top) are not exact and are displayed solely for reference purposes. Shear rate in the brachial artery was calculated for young and old under each of these conditions (bottom). Values are means ± SE. $P < 0.05, diameter changes in old PL trial significantly decreased from those in young PL trial. *P < 0.05, diameter changes during AO trial significantly increased from PL in old subjects. Note young subject data (dashed lines) are presented for reference purposes only (31).

Fig. 3.

Effect of 6 wk of single-leg knee-extensor exercise training on the change in brachial artery diameter (top) and the impact of the AO cocktail on this response after training in old subjects at rest and at 3 levels of handgrip exercise (bottom). Values for %change in brachial diameter are not exact and are displayed solely for reference purposes. It should be noted that baseline resting diameters did not differ as a consequence of exercise training. *P < 0.05, diameter changes during posttraining trial significantly increased from pretraining trial. #P < 0.05, diameter changes during posttraining AO trial significantly decreased from pretraining PL trial.

Fig. 4.

Effect of the oral AO cocktail on the change in brachial artery diameter in old subjects at rest and at 3 levels of handgrip exercise in the exercise-trained and untrained states. Values for %change in brachial diameter are not exact and are displayed solely for reference purposes (top). Shear rate in the brachial artery was calculated under these conditions (bottom). *P < 0.05, significantly different from posttraining AO condition.