Heterogeneity of oxygen diffusion through hamster striated muscles

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Abstract
We determined the O2 diffusion coefficients (DO2) and resting O2 consumptions for three hamster muscles with differing histochemical fiber type composition using a nonsteady-state technique. The muscles ranged from an oxidative muscle (soleus) to a glycolytic muscle (sartorius) with a third, the cheek pouch retractor, having mixed metabolic properties. We found that the DO2 of the soleus (corrected to 37 degrees C) was 2.59 +/- 0.33 X 10(-5) cm2/s, whereas the DO2 of the sartorius was 1.15 +/- 0.14 X 10(-5). The value for the retractor was between these two values (1.39 +/- 0.14 X 10(-5) cm2/s). In addition, we observed a linear correlation between DO2 and the percent of transverse cross-sectional area occupied by oxidative fibers, suggesting that the differences in DO2 can be accounted for by differences in their histochemical fiber type composition. In light of known differences in capillary density and maximal O2 demand, these data imply an interplay between capillarity and O2 diffusion rate resulting in an appropriate O2 delivery to meet each muscle's maximal O2 demand.

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