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.
KeywordsMathematical capillary model Glucose supplying capacity Diffusion across the capillary membrane Convective glucose flux Reflection coefficient
We thank colleagues in the laboratory of Regulation of Tissue Functions at the Department of life Sciences, Ritsumeikan University, for very fruitful discussions.
Compliance with ethical standards
No experimental measurements were carried out in the present study.
Conflict of interest
The authors declare that they have no conflict of interest.
- 22.Levick JR (2013) An introduction to cardiovascular physiology, chapter 10, 5th edn. CRC Press, Boca Raton, FLGoogle Scholar
- 33.Hamilton WF, Dow P (1963) Circulation. Handbook of physiology, Section 2. America Physiological Society, Washington, pp 961–1034Google Scholar
- 34.Hall JE (2015) Guyton and Hall textbook of medical physiology, chapter16. Elsevier Health Sciences, PhiladelphiaGoogle Scholar
- 39.Renkin EM (ed) (1987) Handbook of physiology: Section 2. The cardiovascular system. Microcirculation: pt. 2, vol 4. American Physiological Society, Bethesda, MD, p 431Google Scholar