The influence of flow redistribution on working rat muscle oxygenation

We applied a theoretical model of muscle tissue O2 transport to investigate the effects of flow redistribution on rat soleus muscle oxygenation. The situation chosen was the anaerobic threshold where redistribution of flow is expected to have the largest impact. In the basic situation all capillaries received an equal proportion of the total flow through the tissue, resulting in 4.7% anoxic tissue and a mean tissue PO2 = 3.62 kPa. Both a redistribution of flow where 1) capillaries in blocks of tissue receiving 50% of the basic flow alternated with tissue blocks with capillaries receiving 150% of the basic flow (6.8% anoxic tissue; mean tissue PO2 = 3.32 kPa) and 2) matching flow to 02 consumption (3.3% anoxic tissue; mean tissue PO2 = 3.60 kPa) had little effect. When overall flow was decreased by 20%, the anoxic tissue increased to 7.6% and the mean tissue PO2 decreased to 3.22 kPa. The conclusion from these model calculations is, that flow redistribution has little impact on skeletal muscle oxygenation, which is in line with earlier findings for rat heart.