Send to

Choose Destination
Eur J Appl Physiol. 2009 Jan;105(2):279-87. doi: 10.1007/s00421-008-0901-9. Epub 2008 Nov 7.

Regulation of mitochondrial respiration by inorganic phosphate; comparing permeabilized muscle fibers and isolated mitochondria prepared from type-1 and type-2 rat skeletal muscle.

Author information

Department of Biomedical Sciences, NMR Center, Faculty of Health Sciences,The Panum Institute, The University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark.


ADP is generally accepted as a key regulator of oxygen consumption both in isolated mitochondria and in permeabilized fibers from skeletal muscle. The present study explored inorganic phosphate in a similar regulatory role. Saponin permeabilized fibers and isolated mitochondria from type-I and type-II muscle from male Wistar rats were prepared. Respiration was measured while the medium P(i) concentration was gradually increased. The apparent K(m) values for P(i) were 607 +/- 17 microM and 405 +/- 15 microM (P < 0.0001) for type-I and type-II fibers, respectively. For isolated mitochondria the values were significantly lower than type-1 permeabilized fibers, 338 +/- 130 microM and 235 +/- 30 microM (P < 0.05), but not different with respect to fiber type. The reason for this difference in K(m) values in the permeabilized muscle is unknown, but a similar pattern has been observed for K(m) of ADP. Our data indicate that phosphate may play a role in regulation of oxygen consumption in vitro and in vivo.

[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for Springer
Loading ...
Support Center