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This Article Full Text Full Text (PDF) All Versions of this Article: 285/3/E654    most recent 00119.2003v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (17) Citing Articles via Google Scholar Google Scholar Articles by Zhang, L. Articles by Rattigan, S. Search for Related Content PubMed PubMed Citation Articles by Zhang, L. Articles by Rattigan, S.

TNF- acutely inhibits vascular effects of physiological but not high insulin or contraction

¹Department of Biochemistry, University of Tasmania, Hobart 7001, Australia; and ²Health Sciences Center, University of Virginia, Charlottesville, Virginia 22908

Submitted 20 March 2003 ; accepted in final form 11 May 2003

TNF- is elevated in many states of insulin resistance, and acutely administered TNF- in vivo inhibits insulin-mediated hemodynamic effects and glucose uptake in muscle. In this study, we assess whether the inhibitory effects of TNF- are affected by insulin dose or muscle contraction. Whole body glucose infusion rate (GIR), femoral blood flow (FBF), hindleg vascular resistance, hindleg glucose uptake (HGU), 2-deoxyglucose uptake into muscles of the lower leg (R'g) and hindleg metabolism of infused 1-methylxanthine (1-MX), a measure of capillary recruitment, were determined. Three groups were studied with and without infusion of TNF-: euglycemic insulin-clamped, one-leg field-stimulated (2 Hz, 0.1 ms at 30 V), and saline-infused control anesthetized rats. Insulin infusions were 3, 10, or 30 mU · kg^-1 · min^-1 for 2 h. 1-MX metabolism was maximally increased by all three doses of insulin. GIR, HGU, and R'g were maximal at 10 mU and FBF was maximal at 30 mU of insulin. Contraction increased FBF, HGU, and 1-MX. TNF- (0.5 µg · kg^-1 · h^-1) totally blocked the 3 and 10 mU insulin-mediated increases in FBF and 1-MX, and partly blocked GIR, HGU, and R'g. None of the increases due to twitch contraction was affected by TNF-, and only the increase in FBF due to 30 mU of insulin was partly affected. We conclude that muscle capillary recruitment and glucose uptake due to high levels of insulin or muscle contraction under twitch stimuli at 2 Hz are resistant to TNF-. These findings may have implications for ameliorating muscle insulin resistance resulting from increased plasma TNF- and for the differing mechanisms by which contraction and insulin recruit capillary flow in muscle.

tumor necrosis factor-; diabetes mellitus; blood flow; muscles; inflammation; capillaries

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