Document Detail

Effects of antioxidants on contracting spinotrapezius muscle microvascular oxygenation and blood flow in aged rats.
MedLine Citation:
PMID:  18845782     Owner:  NLM     Status:  MEDLINE    
Aged rats exhibit a decreased muscle microvascular O(2) partial pressure (Pmv(O(2))) at rest and during contractions compared with young rats. Age-related reductions in nitric oxide bioavailability due, in part, to elevated reactive O(2) species, constrain muscle blood flow (Qm). Antioxidants may restore nitric oxide bioavailability, Qm, and ameliorate the reduced Pmv(O(2)). We tested the hypothesis that antioxidants would elevate Qm and, therefore, Pmv(O(2)) in aged rats. Spinotrapezius muscle Pmv(O(2)) and Qm were measured, and oxygen consumption (Vm(O(2))) was estimated in anesthetized male Fisher 344 x Brown Norway hybrid rats at rest and during 1-Hz contractions, before and after antioxidant intravenous infusion (76 mg/kg vitamin C and 52 mg/kg tempol). Before infusion, contractions evoked a biphasic Pmv(O(2)) that fell from 30.6 +/- 0.9 Torr to a nadir of 16.8 +/- 1.2 Torr with an "undershoot" of 2.8 +/- 0.7 Torr below the subsequent steady-state (19.7 +/- 1.2 Torr). The principal effect of antioxidants was to elevate baseline Pmv(O(2)) from 30.6 +/- 0.9 to 35.7 +/- 0.8 Torr (P < 0.05) and reduce or abolish the undershoot (P < 0.05). Antioxidants reduced Qm and Vm(O(2)) during contractions (P < 0.05), while decreasing force production 16.5% (P < 0.05) and elevating the force production-to-Vm(O(2)) ratio (0.92 +/- 0.03 to 1.06 +/- 0.6, P < 0.05). Thus antioxidants increased Pmv(O(2)) by altering the balance between muscle O(2) delivery and Vm(O(2)) at rest and during contractions. It is likely that this effect arose from antioxidants reducing myocyte redox below the level optimal for contractile performance and directly (decreased tension) or indirectly (altered balance of vasoactive mediators) influencing O(2) delivery and Vm(O(2)).
Kyle F Herspring; Leonardo F Ferreira; Steven W Copp; Brian S Snyder; David C Poole; Timothy I Musch
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-10-09
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  105     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2008 Dec 
Date Detail:
Created Date:  2008-12-03     Completed Date:  2009-02-06     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1889-96     Citation Subset:  IM    
Department of Kinesiology, Kansas State University, Manhattan, Kansas 66506-5802, USA.
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MeSH Terms
Aging / physiology*
Antioxidants / pharmacology*
Locomotion / physiology
Microcirculation / drug effects
Muscle Contraction / physiology
Muscle, Skeletal / blood supply*,  growth & development,  metabolism*
Oxygen Consumption / drug effects*
Rats, Inbred BN
Rats, Inbred F344
Regional Blood Flow / drug effects
Reg. No./Substance:
Erratum In:
J Appl Physiol. 2009 Feb;106(2):750

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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