Shallow Intracellular O2 Gradients and Absence of Perimitochondrial O2 “Wells” in Heavily Working Red Muscle
It is generally believed that the principal site of resistance to O2 mass transport resides within the tissue cells.1,2 In this view the ΔPO2 from sarcolemma to cell interior greatly exceeds the ΔPO2 from red cell to interstitium. Precisely the reverse is suggested by recent mathematical models of O2 release from capillaries,3,4,5,6 and by measurements on suspensions of cardiac myocytes in vitro.7 This paper reports the first measurements with sufficient spatial resolution to map intracellular O2 gradients in vivo. We find that the large-scale O2 gradient from sarcolemma to cell interior is indeed shallow, and is not significantly perturbed by small-scale gradients around individual mitochondria.
KeywordsCell Interior Gracilis Muscle Fixed Site Sufficient Spatial Resolution Individual Mitochondrion
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