The role of perfusion in the oxygen extraction capability of skin and skeletal muscle

Abstract

Oxygen extraction (OE) by all cells is dependent on an adequate supply of oxygen in proximal blood vessels and the cell's need and ability to uptake that oxygen. Here the role of blood flow in regulating OE in skin and skeletal muscle was investigated in lean and obese men. OE was derived by two optical reflectance spectroscopy techniques: 1) from the rate of fall in mean blood saturation during a 4 min below knee arterial occlusion, and thus no blood flow, in calf skin and skeletal muscle and 2) in perfused, unperturbed skin, using the spontaneous falls in mean blood saturation induced by vasomotion in calf and forearm skin of 24 subjects, 12 lean and 12 obese. OE in perfused skin was significantly higher in lean compared with obese subjects in forearm (Mann-Whitney, P < 0.004) and calf (P < 0.001) and did not correlate with OE in unperfused skin (ρ = -0.01, P = 0.48). With arterial occlusion and thus no blood flow, skin OE in lean and obese subjects no longer differed (P = 0.23, not significant). In contrast in skeletal muscle with arterial occlusion and no blood flow, the difference in OE between lean and obese subjects occurred, with obese subjects exhibiting significantly higher OE (P < 0.012). The classic model of metabolic blood flow regulation to support oxygen extraction is evident in perfused skin; OE is perturbed without blood flow and reduced in obesity. In resting skeletal muscle other mechanism(s), independent of blood flow, are implicated in oxygen extraction.

Sustained vasomotor control of skin microcirculation in Sherpas versus altitude‐naive lowlanders: Experimental evidence from Xtreme Everest 2

“…Oxygen removal (consumption) by the tissue was estimated as the rate of oxygen desaturation from the decrease in the oxyHb signal during the first 60 s of arterial occlusion (Boas et al, 2011;Thorn et al, 2016). Oxygen removal (consumption) by the tissue was estimated as the rate of oxygen desaturation from the decrease in the oxyHb signal during the first 60 s of arterial occlusion (Boas et al, 2011;Thorn et al, 2016).…”

“…Mean resting values for the oxygenation signals recorded at the forearm (oxyHb, deoxyHb, total Hb and S tO 2 ) were calculated throughout the 5 min before arterial occlusion. Oxygen removal (consumption) by the tissue was estimated as the rate of oxygen desaturation from the decrease in the oxyHb signal during the first 60 s of arterial occlusion (Boas et al, 2011;Thorn et al, 2016).…”

“…Recent studies of skin blood flux and oxygenation signals recorded simultaneously using combined laser Doppler fluximetry (LDF) and white light reflectance spectroscopy have shown these signals to oscillate over broad, generally similar frequency ranges (Bernjak, Stefanovska, McClintock, Owen-Lynch, & Clarkson, 2012, Kuliga et al, 2014. They further suggest that local flowmotion might influence oxygen delivery and extraction (Kuliga, Gush, Clough, & Chipperfield, 2018;Thorn et al 2016;Thorn, Kyte, Slaff, & Shore, 2011). Real-time collection of robust measures of microvascular blood flux and oxygenation parameters might thus provide new information that enhances our understanding of the ways in which the peripheral vasculature of Sherpa highlanders adapts to sustained exposure to hypobaric hypoxia and of how the microcirculation and microvascular perfusion are influenced by hypoxia.…”

“…at 6 and 12 h of exposure to normobaric hypoxia (fraction of inspired O 2 equivalent to 4500 m altitude;Treml et al, 2018). Myogenic activity (vasomotion), which has been shown to be associated closely with effective oxygen delivery and to increase in hypoxia(Bertuglia, Colantuoni, Coppini, & Intaglietta, 1991;Schmidt et al, 1993;Thorn et al 2016), was greater in Sherpas than in lowlanders at baseline in the forearm and at high altitude in the finger. Our findings suggest that Sherpas preserve microcirculatory flow and function at high altitude to a greater degree than lowlanders and are therefore relatively protected from the apparent dysregulation occurring in lowlanders as a component of acclimatization to hypoxia.…”

Time-dependent Behavior of Microvascular Blood Flow and Oxygenation: a Predictor of Functional Outcomes

“…Recent studies in vivo using time series analysis of simultaneously recorded skin blood flux (BF) and oxygenation (OXY) have shown that these signals oscillate over broad, generally similar frequency ranges, with varying total power and relative contribution from low and high frequency power spectral density (PSD) bands [20,21]. They have further shown that the oscillatory properties of blood flux and oxygenation may influence oxygen extraction [22,23]. It remains unclear, however, whether alterations in perfusion complexity and flowmotion control may have functional significance for oxygen delivery and exchange within the microvasculature.…”