Nonlinear Regulation of Capillary Perfusion in Relation to Ambient pO2 Changes in Skeletal Muscle

• Published in: European journal of applied physiology 2005-06, Vol.94 (3), p.352-355
• Main Authors: Shibata, Masahiro, Ichioka, Shigeru, Ando, Joji, Togawa, Tatsuo, Kamiya, Akira
• Format: Article
• Language: English
• Subjects: Recruitment
• ISSN: 1439-6319; 1439-6327
• DOI: 10.1007/s00421-005-1315-6

To study the process of O^sub 2^ transport to tissue, we investigated how capillary perfusion is controlled in response to changes in tissue O^sub 2^ levels in skeletal muscle. Capillary red blood cell (RBC) velocity and perfused capillary recruitment were measured in rabbit tenuissimus muscle at various ambient oxygen tensions (pO^sub 2^) by intravital microscopy. Both RBC velocity and capillary recruitment significantly decreased as the pO^sub 2^ level of the suffusate was increased, and the relationship between capillary perfusion, calculated from the velocity and recruitment data, and the pO^sub 2^ level of the suffusate clearly yielded a nonlinear correlation that fitted a sigmoidal curve. Capillary perfusion dramatically decreases or increases above or below a suffusate pO^sub 2^ level of around 40 Torr, where the O^sub 2^ dissociation curve of hemoglobin changes slope. These findings support the hypothesis that microvasculature possesses an intrinsic, effective flow-control mechanism by sensing the metabolic demands of tissue, intimately related to the O^sub 2^ saturation of hemoglobin.[PUBLICATION ABSTRACT]