title: Local capillary supply in muscle is not determined by local oxidative capacity.
abstract: It is thought that the prime determinant of global muscle capillary density is the mean oxidative capacity. However, feedback control during maturational growth or adaptive remodelling of local muscle capillarisation is likely to be more complex than simply matching O2 supply and demand in response to integrated tissue function. We tested the hypothesis that the maximal oxygen consumption (MO2,max) supported by a capillary is relatively constant, and independent of the volume of tissue supplied (capillary domain). We demonstrate that local MO2,max assessed by succinate dehydrogenase histochemistry: (1) varied more than 100-fold between individual capillaries and (2) was positively correlated to capillary domain area in both human vastus lateralis (R=0.750, P<0.001) and soleus (R=0.697, P<0.001) muscles. This suggests that, in contrast to common assumptions, capillarisation is not primarily dictated by local oxidative capacity, but rather by factors such as fibre size, or consequences of differences in fibre size such as substrate delivery and metabolite removal.
authors.affiliation: Department of Medical, Surgery and Health Sciences, University of Trieste, 34100 Trieste, Italy School of Healthcare Science, Manchester Metropolitan University, Manchester M1 5GD, UK.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Bosutti
authors.affiliation: School of Biomedical Sciences, University of Leeds, Leeds LS2 9JT, UK.
authors.forename: Stuart
authors.initials: S
authors.lastname: Egginton
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Manchester M1 5GD, UK.
authors.forename: Yoann
authors.initials: Y
authors.lastname: Barnouin
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Centre, Linder Höhe, Cologne 51147, Germany.
authors.forename: Bergita
authors.initials: B
authors.lastname: Ganse
authors.affiliation: Institute of Aerospace Medicine, German Aerospace Centre, Linder Höhe, Cologne 51147, Germany.
authors.forename: Jörn
authors.initials: J
authors.lastname: Rittweger
authors.affiliation: School of Healthcare Science, Manchester Metropolitan University, Manchester M1 5GD, UK Lithuanian Sports University, Kaunas LT-44221, Lithuania h.degens@mmu.ac.uk.
authors.forename: Hans
authors.initials: H
authors.lastname: Degens
mesh_terms: D000328:Adult; D002196:Capillaries / Q000502:physiology*; D006801:Humans; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000201:enzymology; D018482:Muscle, Skeletal / Q000098:blood supply* / Q000201:enzymology; D010101:Oxygen Consumption; D013385:Succinate Dehydrogenase / Q000378:metabolism; D055815:Young Adult
chemical_list: D013385:Succinate Dehydrogenase
keywords: Capillarisation; Capillary domains; Muscle; Succinate dehydrogenase