TRASPORTO DELL'OSSIGENO NELL'UOMO ALLE ALTE QUOTE. III. CONTRIBUTO DELLA MIOGLOBINA ALLA DIFFUSIONE DELL'OSSIGENO NELLA FIBRA MUSCOLARE

Translated title of the contribution: Oxygen transport in men at high altitudes. III. Role of myoglobin in oxygen diffusion in muscle fiber

P. Ascenzi, G. Amiconi

Research output: Contribution to journalArticle

Abstract

An adequate O 2 supply to the mitochondria of the skeletal muscles depends on both the partial O 2 pressures in the capillaries and the myoglobin concentration in the muscular fibre. The myoglobin concentration is constant in the cardiac muscle of all adult mammals; on the contrary, in the skeletal muscles it undergoes variation depending on the adaptation to low O 2-pressure or to increased metabolic demand induced by physical training. The myoglobin operates in a state of partial deoxygenation, this implies an oxygen gradient bound to the protein and progressing from the periphery to the axis of the fibre. The same gradient, which has a slope depending on the shape of the dissociation curve of myoglobin-O 2, is very necessary for the contribution of myoglobin to maintain an O 2 flux from capillaries to mitochondria. In fact, the O 2 molecules diffuse through the muscle in any direction whether free or transported by the movements of the protein molecules. Since a gradient of concentration exists, the statistical results of such a process corresponds to the sum of the diffusion flux of the free O 2 and the diffusion flux of the myoglobin-bound O 2. Such a physiochemical phenomenon, i.e. the O 2 diffusion facilitated by myoglobin, has been treated in terms of both translational diffusion of the O 2 molecules bound to the protein and the dissociation rate of O 2 from the myoglobin-oxygen complex. The assumption according to which a chemical equilibrium exists in each point of the muscular fibre, allows the development of a simple equation from which can be calculated the facilitated O 2-diffusion in the muscle; in addition it is possible to conclude that myoglobin is responsible for the O 2 intramolecular transport, specially when the pressure of the gas is low. The contribution of rotational diffusion of myoglobin to the phenomenon of O 2 transport facilitated by this hemoprotein as well as the reserve function of this protein in man are neglible.

Original languageItalian
Pages (from-to)153-163
Number of pages11
JournalMedicina dello Sport
Volume34
Issue number3
Publication statusPublished - 1981

Fingerprint

Myoglobin
Oxygen
Muscles
Pressure
Mitochondria
Skeletal Muscle
Proteins
Facilitated Diffusion
Mammals
Myocardium
Gases

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Public Health, Environmental and Occupational Health
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

TRASPORTO DELL'OSSIGENO NELL'UOMO ALLE ALTE QUOTE. III. CONTRIBUTO DELLA MIOGLOBINA ALLA DIFFUSIONE DELL'OSSIGENO NELLA FIBRA MUSCOLARE. / Ascenzi, P.; Amiconi, G.

In: Medicina dello Sport, Vol. 34, No. 3, 1981, p. 153-163.

Research output: Contribution to journalArticle

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