Regulation of the glucose supply from capillary to tissue examined by developing a capillary model

A new glucose transport model relying upon diffusion and convection across the capillary membrane was developed, and supplemented with tissue space and lymph flow. The rate of glucose utilization (J _util) in the tissue space was described as a saturation function of glucose concentration in the interstitial fluid (C _glu,isf), and was varied by applying a scaling factor f to J _max. With f = 0, the glucose diffusion ceased within ~20 min. While, with increasing f, the diffusion was accelerated through a decrease in C _glu,isf, but the convective flux remained close to resting level. When the glucose supplying capacity of the capillary was measured with a criterion of J _util /J _max = 0.5, the capacity increased in proportion to the number of perfused capillaries. A consistent profile of declining C _glu,isf along the capillary axis was observed at the criterion of 0.5 irrespective of the capillary number. Increasing blood flow scarcely improved the supplying capacity.