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Facilitated diffusion of myoglobin and creatine kinase and reaction–diffusion constraints of aerobic metabolism under steady‐state conditions in skeletal muscle
Author(s) -
Dasika S.K.,
Kinsey S.T.,
Locke B.R.
Publication year - 2012
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.23329
Subject(s) - diffusion , skeletal muscle , myoglobin , steady state (chemistry) , biophysics , context (archaeology) , chemistry , creatine kinase , oxygen , biochemistry , biology , thermodynamics , anatomy , paleontology , physics , organic chemistry
The roles of creatine kinase (CK) and myoglobin (Mb) on steady‐state facilitated diffusion and temporal buffering of ATP and oxygen, respectively, are assessed within the context of a reaction–diffusion model of muscle energetics. Comparison of the reaction–diffusion model with experimental data from a wide range of muscle fibers shows that the experimentally observed skeletal muscle fibers are generally not limited by diffusion, and the model further indicates that while some muscle fibers operate near the edge of diffusion limitation, no detectable effects of Mb and CK on the effectiveness factor, a measure of diffusion constraints, are observed under steady‐state conditions. However, CK had a significant effect on average ATP concentration over a wide range of rates and length scales within the reaction limited regime. The facilitated diffusion functions of Mb and CK become observable in the model for larger size cells with low mitochondrial volume fraction and for low boundary O 2 concentration and high ATP demand, where the fibers may be limited by diffusion. From the transient analysis it may be concluded that CK primarily functions to temporally buffer ATP as opposed to facilitating diffusion while Mb has a small temporal buffering effect on oxygen but does not play any significant role in steady‐state facilitated diffusion in skeletal muscle fibers under most physiologically relevant regions. Biotechnol. Bioeng. 2012; 109:545–558. © 2011 Wiley Periodicals, Inc.