European Journal of Applied Physiology

, Volume 105, Issue 2, pp 279–287

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

Original Article

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 Pi concentration was gradually increased. The apparent Km values for Pi were 607 ± 17 µM and 405 ± 15 μM (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 μM and 235 ± 30 μM (P < 0.05), but not different with respect to fiber type. The reason for this difference in Km values in the permeabilized muscle is unknown, but a similar pattern has been observed for Km of ADP. Our data indicate that phosphate may play a role in regulation of oxygen consumption in vitro and in vivo.

Keywords

Mitochondrial respiration Permeabilized muscle Inorganic phosphate Striated muscle Oxygen consumption Oxidative phosphorylation 

Abbreviations

ADP

Adenosine 5′-diphosphate

AMP

Adenosine 5′-monophosphate

ATP

Adenosine 5′-triphosphate

BSA

Bovine serum albumin

DTT

Dithiotreitol

EDL

Extensor digotorum longus

EDTA

Ethylenediaminetetraacetic acid

EGTA

Ethylene glycol-bis (2-aminoethylether)-N, N, NN′-tetraacetic acid

FCCP

Carbonyl cyanide 4-(triflouromethoxy) phenylhydrazone

FID

Free induction decay

GAP

Glyceraldehyde-3-phosphate

GAPDH

Glyceraldehyde-3-phosphate dehydrogenase

HSS

High speed spin

LSS

Low speed spin

MES

2-(N-morpholino) ethanesulfonic acid hydrate

MHC

Myosine heavy chain

NAD

Nicotinamide adenine dinucleotide

PCr

Phosphocreatine

Pi

Inorganic phosphate

31P-NMRS

31Phosphorous nuclear magnetic resonance spectroscopy

RCR

Respiratory control ratio

SDS

Sodium dodecyl sulfate

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  1. 1.Department of Biomedical Sciences, NMR Center, Faculty of Health Sciences,The Panum InstituteThe University of CopenhagenCopenhagenDenmark

Personalised recommendations