Blood temperature and perfusion to exercising and non‐exercising human limbs

Abstract

New Findings What is the central question of this study? Temperature‐sensitive mechanisms are thought to contribute to blood‐flow regulation, but the relationship between exercising and non‐exercising limb perfusion and blood temperature is not established. What is the main finding and its importance? The close coupling among perfusion, blood temperature and aerobic metabolism in exercising and non‐exercising extremities across different exercise modalities and activity levels and the tight association between limb vasodilatation and increases in plasma ATP suggest that both temperature‐ and metabolism‐sensitive mechanisms are important for the control of human limb perfusion, possibly by activating ATP release from the erythrocytes. Temperature‐sensitive mechanisms may contribute to blood‐flow regulation, but the influence of temperature on perfusion to exercising and non‐exercising human limbs is not established. Blood temperature (T B), blood flow and oxygen uptake (trueV˙O2) in the legs and arms were measured in 16 healthy humans during 90 min of leg and arm exercise and during exhaustive incremental leg or arm exercise. During prolonged exercise, leg blood flow (LBF) was fourfold higher than arm blood flow (ABF) in association with higher T B and limb trueV˙O2. Leg and arm vascular conductance during exercise compared with rest was related closely to T B (r 2 = 0.91; P < 0.05), plasma ATP (r 2 = 0.94; P < 0.05) and limb V˙normalO2 (r 2 = 0.99; P < 0.05). During incremental leg exercise, LBF increased in association with elevations in T B and limb trueV˙O2, whereas ABF, arm T B and V˙normalO2 remained largely unchanged. During incremental arm exercise, both ABF and LBF increased in relationship to similar increases in trueV˙O2. In 12 trained males, increases in femoral T B and LBF during incremental leg exercise were mirrored by similar pulmonary artery T B and cardiac output dynamics, suggesting that processes in active limbs dominate central temperature and perfusion responses. The present data reveal a close coupling among perfusion, T B and aerobic metabolism in exercising and non‐exercising extremities and a tight association between limb vasodilatation and increases in plasma ATP. These findings suggest that temperature and V˙normalO2 contribute to the regulation of limb perfusion through control of intravascular ATP.

Computational Fluid Dynamics Analysis of Cold Plasma Plume Mixing with Blood Using Level Set Method Coupled with Heat Transfer

“…The initial temperature of blood was set to be 310 K [38] and the initial cold plasma temperature was set to be at 303 K [39]. In the FEM technique, an element consisted of a number of nodes, each associated with a shape function (Ni) and a temperature (Ti), so the element temperature would be ∑ , where Telement was the temperature in the element, M was the total number of nodes in a specific element, Ni and Ti were the shape function and temperature of the i th node within the element, respectively.…”

“…The initial temperature of blood was set to be 310 K [38] and the initial cold plasma temperature was set to be at 303 K [39]. In the FEM technique, an element consisted of a number of nodes, each associated with a shape function (N i ) and a temperature (T i ), so the element temperature would be…”

“…Furthermore, the temperatures for blood and plasma at the inlet nozzles were assumed constants as 310 and 303 K, respectively [38,39].…”

Mechanisms for the control of local tissue blood flow during thermal interventions: influence of temperature‐dependent ATP release from human blood and endothelial cells

“…1995; González‐Alonso et al . 2002, 2015), is overridden during passive heating in vivo because venous O 2 saturation and tension increase drastically when O 2 delivery rises in the face of an unchanged metabolic demand. In contrast to the responses to heating, plasma [ATP] did not change with graded cooling in vivo .…”

“…1995; González‐Alonso et al . 2002, 2015; Gourine et al . 2010), because metabolic changes in response to local heating and cooling are relatively small (Barcroft & Edholm, 1943; Pearson et al .…”