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|Title:||Local temperature-sensitive mechanisms are important mediators of limb tissue hyperemia in the heat-stressed human at rest and during small muscle mass exercise.|
|Keywords:||Exercise;Heat stress;Leg blood flow|
|Publisher:||American Physiological Society|
|Citation:||American Journal of Physiology - Heart and Circulatory Physiology , 309(2): H369-H380, (15 July 2015)|
|Abstract:||Limb tissue and systemic blood flow increases with heat stress, but the underlying mechanisms remain poorly understood. Here, we tested the hypothesis that heat stress-induced increases in limb tissue perfusion are primarily mediated by local temperature-sensitive mechanisms. Leg and systemic temperatures and hemodynamics were measured at rest and during incremental single-legged knee extensor exercise in 15 males exposed to 1 h of either systemic passive heat-stress with simultaneous cooling of a single leg (n=8) or isolated leg heating or cooling (n=7). Systemic heat-stress increased core, skin and heated leg blood (Tb) temperatures, cardiac output and heated leg blood flow (LBF, 0.6 ± 0.1 l.min(-1); P<0.05). In the cooled leg, however, LBF remained unchanged throughout (P>0.05). Increased heated leg deep tissue BF was closely related to Tb (R(2) = 0.50; P<0.01), which is partly attributed to increases in tissue V̇O2 (R(2) = 0.55; P<0.01) accompanying elevations in total leg glucose uptake (P<0.05). During isolated limb heating and cooling, LBFs were equivalent to those found during systemic heat-stress (P>0.05), despite unchanged systemic temperatures and hemodynamics. During incremental exercise, heated LBF was consistently maintained ~ 0.6 l.min(-1) higher than that in the cooled leg (P<0.01), with LBF and vascular conductance in both legs showing a strong correlation with their respective local Tb (R(2) = 0.85 and 0.95, P<0.05). We conclude that local temperature-sensitive mechanisms are important mediators in limb tissue perfusion regulation both at rest and during small-muscle mass exercise in hyperthermic humans.|
|Appears in Collections:||Dept of Life Sciences Research Papers|
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