High lipid content enhances the rate of oxygen diffusion through fish skeletal muscle
Desaulniers, N.; Moerland, T.S.; Sidell, B.D.
American Journal of Physiology 271(1 Pt 2): R42-R47
1996
ISSN/ISBN: 0002-9513 PMID: 8760202 Document Number: 455221
The diffusion coefficient for O-2 (D-O-2) and the solubility constant for O-2 (alpha-O-2) were measured at 15 degree C in oxidative muscle from striped bass (Morone saxatilis) that had been acclimated to 5 degree and 25 degree C. This design allowed us to test the hypothesis that changes in composition of the tissue that are known to occur during thermal acclimation may affect O-2 movement. Our measurements permitted calculation of the diffusion constant for O-2 (K-O-2) through the tissue, which is a primary determinant of capacity for O-2 flux. Under isothermal conditions, alpha-O-2 was 3.59 +- 0.20 times 10-2 and 6.64 +- 0.27 times 10-2 ml O-2 cntdot cm-3 cntdot atm-1 in tissues from 25 degree - and 5 degree C-acclimated animals, respectively. Because O-2 is more soluble in lipid than aqueous phase, higher alpha-O-2 in tissues from cold-acclimated animals can be accounted for by the 13-fold increase in lipid content that is known to occur in oxidative muscle of striped bass during acclimation from 25 degree to 5 degree C. When measured under similar isothermal conditions, D-O-2 showed no significant difference between animals acclimated to warm or cold temperature; D-O-2 through tissues from 25 degree - and 5 degree C-acclimated animals was 2.50 +- 0.18 and 2.57 +- 0.40 cm-2/s, respectively. Because alpha-O-2 increases, the calculated K-O-2 (D-O-2 cntdot alpha-O-2) is greater in tissue from cold- than from warm-acclimated fish. At physiological temperature, elevated lipid content in oxidative muscle of cold-acclimated striped bass should result in enhanced intracellular movement of O-2 and at least partially offset the expected decrease in D-O-2 at cold temperature.