Effects of cold acclimation and palmitate on energy coupling in duckling skeletal muscle mitochondria.
Gastrocnemius subsarcolemmal and intermyofibrillar mitochondria were isolated from 5-week-old cold-acclimated and thermoneutral control ducklings. In vitro respiration (polarography) and ATP synthesis (bioluminescence) were determined at 25 degrees C. Subsarcolemmal mitochondria showed a higher state 4 respiration and lower respiratory control and ADP/O ratio in cold-acclimated than in thermoneutral ducklings. Palmitate decreased the rate of ATP synthesis in both mitochondrial populations to about 30% of maximal but failed to abolish this process even at high concentrations. It is suggested that both expensive ATP synthesis and increased ATP hydrolysis could contribute synergistically to muscle non-shivering thermogenesis in cold-acclimated ducklings.
Roussel
D
D
Laboratoire de Physiologie des Régulations Energétiques, Cellulaires et Moléculaires, UMR 5578 CNRS-UCBL, Lyon, France. dbjr1@le.ac.uk
Rouanet
J L
JL
Duchamp
C
C
Barré
H
H
D000064:Acclimatization; D000255:Adenosine Triphosphate / Q000096:biosynthesis; D000818:Animals; D019069:Cell Respiration; D003080:Cold Temperature; D004372:Ducks; D004734:Energy Metabolism; D008297:Male; D008564:Membrane Potentials; D008931:Mitochondria, Muscle / Q000378:metabolism*; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D010168:Palmitates / Q000378:metabolism*; D012508:Sarcolemma / Q000378:metabolism
D010168:Palmitates; D000255:Adenosine Triphosphate