Local capillary supply in muscle is not determined by local oxidative capacity

Bosutti, A, Egginton, S, Barnouin, Y, Ganse, B, Rittweger, J and Degens, H (2015) Local capillary supply in muscle is not determined by local oxidative capacity. Journal of experimental biology, 218. ISSN 0022-0949

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Abstract

It is thought that the prime determinant of global muscle capillary density is the mean 40 oxidative capacity. However, feedback control during maturational growth or adaptive 41 remodelling of local muscle capillarisation is likely more complex than simply matching O2 42 supply and demand in response to integrated tissue function. We tested the hypothesis that 43 the maximal oxygen consumption (MO2max) supported by a capillary is relatively constant, 44 and independent of the volume of tissue supplied (capillary domain). We demonstrate that 45 local MO2max assessed by succinate dehydrogenase histochemistry 1) varied more than 100- 46 fold between individual capillaries and 2) was positively correlated to capillary domain area 47 in both human vastus lateralis (R=0.750, P<0.001) and soleus (R=0.697, P<0.001) muscles. 48 This suggests that, in contrast to common assumptions, capillarisation is not primarily 49 dictated by local oxidative capacity, but rather by factors such as fibre size, or consequences 50 of differences in fibre size such as substrate delivery/metabolite removal.