Ascorbic acid does not affect the age-associated reduction in maximal cardiac output and oxygen consumption in healthy adults

Bell, Christopher; Carson, John M.; Motte, Nathaniel W.; Seals, Douglas R.

doi:10.1152/japplphysiol.00790.2004

Cited by 25 publications

(28 citation statements)

References 42 publications

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“…It is important to consider differences in small compared with large muscle mass exercise and locomotor muscles compared with nonlocomotor skeletal muscle along with possible species-specific effects when examining these differences. However, the present data are generally consistent with the report that acute AA infusion did not alter maximal exercise cardiac output or oxygen consumption in older humans (Bell et al 2005). Interestingly, the AA-induced vasoconstriction evident at rest was abolished during exercise.…”

Section: Comparison With the Literaturesupporting

confidence: 93%

Acute ascorbic acid and hindlimb skeletal muscle blood flow distribution in old rats: rest and exercise

Copp

Schwagerl

Hirai

et al. 2012

Can. J. Physiol. Pharmacol.

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Excess reactive oxygen species are implicated in the impaired peripheral vascular function evident during exercise in older individuals. We tested the hypothesis that an acute infusion of the antioxidant ascorbic acid (AA) in old rats would improve antioxidant capacity and reduce oxidative stress and, therefore, elevate hindlimb muscle blood flow at rest and during treadmill exercise in muscles containing principally type I and IIa muscle fibers. Total and individual hindlimb skeletal muscle blood flow was measured (radiolabeled microspheres) in old rats (26-28 months) at rest (n = 8) and during treadmill exercise (n = 8; 20 m·min⁻¹, 5% grade) before and after AA treatment (76 mg·(kg body mass)⁻¹ intra-arterial (i.a.) injection). AA elevated total antioxidant capacity (rest, ~37%; and exercise, 31%) and reduced oxidative stress (~26%, exercise only). AA reduced resting total hindlimb muscle blood flow (control, 25 ± 3; AA, 16 ± 2 mL·min⁻¹·(100 g)⁻¹; p < 0.05) and blood flow to 8 of 28 individual muscles with no fiber-type correlation (p > 0.05). During exercise there was no effect of AA on total hindlimb muscle blood flow (control, 154 ± 14; AA, 162 ± 13 mL·min⁻¹·(100 g)⁻¹; p > 0.05) or blood flow to any individual muscle. This disconnect between whole-body antioxidant status and skeletal muscle blood flow in old rats mandates consideration when pursuing antioxidant treatments experimentally or clinically in older populations.

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Section: Comparison With the Literaturesupporting

confidence: 93%

Acute ascorbic acid and hindlimb skeletal muscle blood flow distribution in old rats: rest and exercise

Copp

Schwagerl

Hirai

et al. 2012

Can. J. Physiol. Pharmacol.

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“…Second, we did not measure ascorbic acid concentrations or oxidative stress markers during the infusions. However, we have shown previously that the same infusion dose of ascorbic acid increases plasma ascorbic acid to supraphysiological levels (Ϸ15-fold higher than baseline levels) 25,26,[43][44][45] and decreases plasma oxidized LDL and isoprostane concentrations. 43,44 Moreover, in the present study, we were able to demonstrate a significant increase in large elastic artery compliance with ascorbic acid in the postmenopausal women, the group postulated to have baseline oxidative stress.…”

Section: Considerations and Experimental Limitationsmentioning

confidence: 81%

Ascorbic Acid Selectively Improves Large Elastic Artery Compliance in Postmenopausal Women

et al. 2005

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Abstract-The compliance of large elastic arteries in the cardiothoracic region decreases with advancing age/menopause and plays an important role in the increased prevalence of cardiovascular diseases in postmenopausal women. We determined whether oxidative stress contributes to the reduced large elastic artery compliance of postmenopausal women. Carotid artery compliance was measured during acute intravenous infusions of saline (baseline control) and supraphysiological doses of the potent antioxidant ascorbic acid in premenopausal (nϭ10; 23Ϯ1; meanϮSE) and estrogen-deficient postmenopausal (nϭ21; 55Ϯ1 years) healthy sedentary women. Carotid artery compliance was 56% lower in postmenopausal compared with premenopausal women during baseline control (PϽ0.0001 ). Carotid artery diameter, blood pressure, and heart rate were unaffected by ascorbic acid. In the pooled population, the change in arterial compliance with ascorbic acid correlated with baseline waist-to-hip ratio (rϭ0.56; Pϭ0.001), plasma norepinephrine (rϭ0.58; Pϭ0.001), and LDL cholesterol (rϭ0.54; Pϭ0.001). These results suggest that oxidative stress may be an important mechanism contributing to the reduced large elastic artery compliance of sedentary, estrogen-deficient postmenopausal women. Increased abdominal fat storage, sympathetic nervous system activity, and LDL cholesterol may be mechanistically involved in oxidative stress-associated suppression of arterial compliance in postmenopausal women. Key Words: aging Ⅲ cholesterol Ⅲ oxidative stress C ardiovascular disease (CVD) is the leading cause of death in women in the United States. 1 "Vascular aging" has been emphasized recently as the major risk factor for development of CVD. 2 One clinically important change that occurs with vascular aging is a reduction in the compliance of large elastic arteries within the cardiothoracic region. In turn, this contributes to a number of adverse age-associated changes, including increased aortic impedance, left ventricular hypertrophy, and reduced cardiovagal baroreflex sensitivity. [2][3][4] As such, identifying the mechanisms that contribute to reduced large elastic artery compliance with age is an important goal. 2 Cardiovascular aging in women is unique in that it appears to be delayed or occurs at a slower rate than in men during the premenopausal years, thereafter "catching up" with men during the postmenopausal period, particularly in estrogendeficient women. [5][6][7] The mechanisms underlying the accelerated cardiovascular aging of estrogen-deficient postmenopausal women are unclear but could be related in part to the development of oxidative stress. Markers of oxidative stress are higher and endogenous antioxidant defenses lower in some estrogen-deficient postmenopausal women compared with premenopausal controls. 8,9 Because oxidative stress modulates vascular smooth muscle cell (VSMC) tone, a key determinant of large artery compliance, 10,11 we hypothesized that oxidative stress may contribute to the reduced large artery compliance of estrogen-defic...

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“…Cardiac output was determined via open-circuit acetylene breathing (Beck Integrated Physiological Testing System, St. Paul, MN, USA) as previously described (5, 6, 20). Three measurements of cardiac output were made immediately prior to exercise, with the subject seated quietly on the cycle ergometer, and three during maximal exercise.…”

Section: Methodsmentioning

confidence: 99%

Epigallocatechin-3-gallate Increases Maximal Oxygen Uptake in Adult Humans

Richards

Lonac

Johnson

et al. 2010

Medicine &Amp; Science in Sports &Amp; Exercise

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Epigallocatechin-3-gallate (EGCG), a component of green tea, increases endurance performance in animals and promotes fat oxidation during cycle ergometer exercise in adult humans. Purpose We have investigated the hypothesis that short-term consumption of EGCG delays the onset of the ventilatory threshold (TVE) and increases maximal oxygen uptake (VO2max). Methods In this randomized, repeated measures, double blind study, 19 healthy adults (11 males, 8 females, age: 26 ± 2 years (mean ± SE)) received 7 placebo or 7 EGCG (135 mg) pills. 48-hours prior to data collection participants began consuming 3 pills per day; the last pill was taken 2-hours before exercise testing. TVE and VO2max were determined from breath-by-breath indirect calorimetry data collected during continuous incremental stationary cycle ergometer exercise (20-35 W/min), from rest until volitional fatigue. Each condition/exercise test was separated by a minimum of 14-days. Results Compared with placebo, short-term EGCG consumption increased VO2max (3.123 ± 0.187 vs. 3.259 ± 0.196 L·min-1, P=0.04). Maximal work rate (301 ± 15 vs. 301 ± 16 W, P=0.98), maximal respiratory exchange ratio (1.21 ± 0.01 vs. 1.22 ± 0.02, P=0.27), and maximal heart rate were unaffected (180 ± 3 vs. 180 ± 3 beats·min-1, P=0.87). In a subset of subjects (n=11) maximal cardiac output (determined via open-circuit acetylene breathing) was also unaffected by EGCG (29.6 ± 2.2 vs. 30.2 ± 1.4 L·min-1, P=0.70). Contrary to our hypothesis, EGCG decreased VO2 at TVE (1.57 ± 0.11 vs. 1.48 ± 0.10 L·min-1) but this change was not significant (P=0.06). Conclusion Short-term consumption of EGCG increased VO2max without affecting maximal cardiac output, suggesting that EGCG may increase arterial-venous oxygen difference.

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Ascorbic acid does not affect the age-associated reduction in maximal cardiac output and oxygen consumption in healthy adults

Cited by 25 publications

References 42 publications

Acute ascorbic acid and hindlimb skeletal muscle blood flow distribution in old rats: rest and exercise

Acute ascorbic acid and hindlimb skeletal muscle blood flow distribution in old rats: rest and exercise

Ascorbic Acid Selectively Improves Large Elastic Artery Compliance in Postmenopausal Women

Epigallocatechin-3-gallate Increases Maximal Oxygen Uptake in Adult Humans

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