Oxygen Transport to Tissue during Recurrent Blood Flow Supply by Grouped Capillaries in Skeletal Muscle with or without Facilitated Diffusion

Abstract

Intravital observations of the microcirculation in various skeletal muscles have revealed that the capillary red cell velocity in the resting state is neither steady nor uniform (Wiedeman, 1984). It often fluctuates periodically and capillaries seem to repeat intermittently open and closed phases of flow with a frequency of 0.05 Hz to 0.2 Hz (Lindbom et al., 1980; Shibata et al., 1983). In the previous study (Fukuoka et al., 1983), the effects of such an intermittent capillary flow on oxygen (O₂) transport to tissue was analyzed with a dynamic computor simulation. Tne result demonstrated that when a tissue region is supplied with O₂ recurrently from one of the surrounding capillaries, the lowest level of O₂ tension (PO₂) in the tissue becomes substantially higher than that perfused continuously by a certain fixed capillary with the same blood flow. However, further detailed observation of the skeletal muscle microcirculation has shown that tissue is supplied with O₂ by several grouped capillaries, which originate from the same arteriole and repeat the open and closed phases simultaneously in each group but out of phase to other groups (Shibata et al., 1985). In this study we tried to evaluate the effect of the intermittent capillary flow on oxygen transport to tissue by employing a more realistic model of recurrent blood flow supply by grouped capillaries. The influence of the facilitated diffusion by myoglobin (Mb) on the transport (Kreuzer, 1970) was also analysed in this model.