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

• Published in: Canadian journal of physiology and pharmacology 2012-11, Vol.90 (11), p.1498-1505
• Main Authors: COPP, Steven W, SCHWAGERL, Peter J, HIRAI, Daniel M, POOLE, David C, MUSCH, Timothy I
• Format: Article
• Language: English
• Subjects: Aging; Animals; Animals, Outbred Strains; Antioxidants; Antioxidants - administration & dosage; Antioxidants - metabolism; Antioxidants - therapeutic use; antioxydants; Ascorbic Acid - administration & dosage; Ascorbic Acid - therapeutic use; Biological and medical sciences; Biomarkers - blood; Biomarkers - metabolism; Blood; Blood flow; Combined Modality Therapy; Control; contrôle vasculaire; espères réactives d’oxygène; Exercise; Fundamental and applied biological sciences. Psychology; Hindlimb; Infusions, Intravenous; Motor Activity; Muscle Fibers, Fast-Twitch - metabolism; Muscle Fibers, Slow-Twitch - metabolism; Muscle, Skeletal - blood supply; Muscle, Skeletal - metabolism; Muscles; Musculoskeletal system; Oxidative Stress; Peripheral Vascular Diseases - blood; Peripheral Vascular Diseases - metabolism; Peripheral Vascular Diseases - therapy; Physiological aspects; Rats; Rats, Inbred F344; Reactive oxygen species; Regional Blood Flow; Rodents; stress oxydant; vascular control; vasodilatation; vasodilation; Vertebrates: anatomy and physiology, studies on body, several organs or systems; vieillissement; Vitamin C; vitamine C
• ISSN: 0008-4212; 1205-7541
• DOI: 10.1139/y2012-109

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.