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Acute Antioxidant (AOX) Treatment Increases Muscle Microvascular O 2 Extraction in Young Rats
Author(s) -
Copp Steven W,
Hirai Daniel M,
Schwagerl Peter J,
Herspring Kyle F,
Musch Timothy I,
Poole David C
Publication year - 2009
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.23.1_supplement.948.3
Subject(s) - chemistry , zoology , antioxidant , endocrinology , medicine , biochemistry , biology
AOX treatment (76 mg/kg vitamin C, 52 mg/kg tempol) elevates microvascular O 2 pressures (PO 2 mv ) at rest and following the onset of muscle contractions in aged (A) rats reducing fractional O 2 extraction (Herspring et al. J. Appl. Physiol. 2008). PURPOSE To test the hypothesis that this specific AOX treatment would elevate PO 2 mv in the spinotrapezius muscle of young (Y) rats at rest and during contractions. METHODS PO 2 mv , which reflects the dynamic balance between O 2 delivery/utilization (fractional O 2 extraction), was measured via phosphorescence quenching in the spinotrapezius of 12 Y (6‐8 mo) and 15 A (26‐30 mo) Fisher 344 x BN rats. Electrically‐induced contraction bouts (1 Hz twitch) were performed with and without (CON) intra‐arterial AOX administration. The PO 2 mv response was fitted with an exponential model and compared using two‐way ANOVA (age x condition). RESULTS The CON baseline PO 2 mv was not different (P>0.05) between Y (31±4 mmHg) and A (30±3 mmHg). However, AOX decreased baseline PO 2 mv in Y (25±5 mmHg) whilst it was increased in A (36±3 mmHg) (both P<0.05). Moreover, throughout contractions in Y, AOX decreased PO 2 mv below CON values by 21 + 6% on average (P<0.05). CONCLUSIONS The impact of AOX supplementation on PO 2 mv is age‐dependent. In contrast to A rats, in Y rats, AOX reduced PO 2 mv (increased fractional O 2 extraction) at rest and during contractions. Support: AHA, Heartland Affiliate 0750090Z