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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

1
Department of Biomedical Sciences, NMR Center, Faculty of Health Sciences,The Panum Institute, The University of Copenhagen, Blegdamsvej 3, 2200 Copenhagen, Denmark. morten@forsoegsperson.dk

Abstract

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.

PMID:
18989695
DOI:
10.1007/s00421-008-0901-9
[Indexed for MEDLINE]

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