Oxygen Diffusion Coefficient in Isolated Chicken Red and White Skeletal Muscle Fibers in Ontogenesis

Author： Baranov V.I. Belichenko V.M. Shoshenko C.A.

ISSN： 0026-2862

Source： Microvascular Research, Vol.60, Iss.2, 2000-09, pp. : 168-176

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Abstract

Oxygen diffusion from medium to cultured isolated muscle fibers from red gastrocnemius muscle (deep part) (RGM) and white pectoralis muscle (WPM) of embryonic and postnatal chickens (about 6 months) was explored. The intracellular effective O₂ diffusion coefficient (D_i) in muscle fiber was calculated from a model of a cylindrical fiber with a uniform distribution of an oxygen sink based on these experimentally measured parameters: critical tension of O₂ (PO₂) on the surface of a fiber, specific rate of O₂ consumption by a weight unit of muscle fibers (·VO₂), and average diameter of muscle fibers. The results document the rapid hypertrophic growth of RGM fibers when compared to WPM fibers in the second half of the embryonic period and the higher values of ·VO₂ and critical PO₂ during the ontogenetic period under study. The oxygen D_i in RGM fibers of embryos and 1-day chickens was two to three times higher than observed for WPM fibers. For senior chickens, the oxygen D_i value in RGM and WPM fibers does not differ. The D_i of O₂ in both RGM and WPM fibers increased from 1.4–2.7 × 10^-8 to 90–95 × 10^-8 cm²/s with an ontogenetic increase in fiber diameter from 7.5 to 67.0 μm. At all stages the oxygen D_i values in RGM and WPM fibers are significantly lower than the O₂ diffusion coefficient in water: for 11-day embryos they are 889 and 1714 times lower and for adult individuals 25 and 27 times lower, respectively. Why oxygen D_i values in RGM and WPM fibers are so low and why they are gradually increasing during the course of hypertrophic ontogenetic growth are still unclear.