Oxygen flux

high-resolution terminology - matching measurements at high-resolution

Oxygen flux

Description

Oxygen flux, J_O₂, is a specific quantity. Oxygen flux is oxygen flow, I_O₂ [mol·s^-1 per system] (an extensive quantity), divided by system size. Flux may be volume-specific (flow per volume [pmol·s^-1·mL^-1]), mass-specific (flow per mass [pmol·s^-1·mg^-1]), or marker-specific (flow per mtEU). Oxygen flux (e.g., per body mass, or per cell volume) is distinguished from oxygen flow (per number of objects, such as cells), I_O₂ [mol·s^-1·x^-1]. These are different forms of normalization of rate.

Abbreviation: J_O2

Reference: BEC 2020.1, Gnaiger 2020 BEC MitoPathways, Gnaiger 1993 Pure Appl Chem, Renner 2003 Biochim Biophys Acta

Contributed by Gnaiger E (2020-01-15)

Which SI units should be used?

The SI unit for volume

1000 L = 1 m³

1 L = 1 dm³

1 mL = 1 cm³

1 µL = 1 mm³

Convert various units of volume-specific oxygen flux, J_O₂, to SI units [nmol·s^-1·L^-1] = [pmol·s^-1·mL^-1]

1 µmol O₂∙min^-1∙L^-1 ∙ [1000 nmol∙(1 µmol)^-1] ∙ [1 min∙(60 s)^-1] = 16.67 nmol O₂∙s^-1∙L^-1

1 nmol O₂∙min^-1∙mL^-1 ∙ [1000 pmol∙(1 nmol)^-1] ∙ [1 min∙(60 s)^-1] = 16.67 pmol O₂∙s^-1∙mL^-1

1 nmol O₂∙h^-1∙mL^-1 ∙ [1000 pmol∙(1 nmol)^-1] ∙ [1 min∙(60 s)^-1] ∙ [1 h∙(60 min)^-1] = 0.2778 pmol O₂∙s^-1∙mL^-1

1 natom O∙s^-1∙L^-1 ∙ [1 nmol O₂∙(2 natm O)^-1] = 0.5 nmol O₂∙s^-1∙L^-1

1 natom O∙min^-1∙L^-1 ∙ [1000 pmol O₂∙(2 natom O)^-1] ∙ [1 min∙(60 s)^-1] = 8.33 pmol O₂∙s^-1∙L^-1

Convert V_O₂max/M from ergometric to SI units

1 mL O₂∙min^-1∙kg^-1 (at STPD) ∙ [1000 µmol∙(22.392 mL)^-1] ∙ [1 min∙(60 s)^-1] = 0.744 µmol O₂∙s^-1∙kg^-1

There is a difference between oxygen flux per volume and oxygen concentration change per time

The oxygen concentration change per time (= rate of concentration change) is expressed in units [µmol O₂∙L^-1∙s^-1].

By definition the rate of concentration change is zero in an open system at steady-state, when the concentration in the system does not change at any respiratory flux by the sample enclosed in the open system.

Oxygen flux per volume (= volume-specific oxygen flux) is expressed in units [µmol O₂∙s^-1∙L^-1] or [nmol O₂∙s^-1∙L^-1]

By definition the volume-specific oxygen flux is the advancement of reaction per volume of the reaction chamber.

Oxygen flux per mass (= mass-specific oxygen flux) is expressed in units [µmol O₂∙s^-1∙kg^-1] = [pmol O₂∙s^-1∙mg^-1]

By definition the mass-specific oxygen flux is the advancement of reaction per mass of the sample enclosed in the reaction chamber.

References

Bioblast link	Reference	Year
BEC 2020.1 doi10.26124bec2020-0001.v1	Gnaiger E et al ― MitoEAGLE Task Group (2020) Mitochondrial physiology. Bioenerg Commun 2020.1. https://doi.org/10.26124/bec:2020-0001.v1	2020