Skeletal muscle oxidative capacity in rats fed high-fat diet.
OBJECTIVE
To investigate whether young rats respond to high-fat feeding through changes in energy efficiency and fuel partitioning at the level of skeletal muscle, to avoid obesity development. In addition, to establish whether the two mitochondrial subpopulations, which exist in skeletal muscle, ie subsarcolemmal and intermyofibrillar, are differently affected by high-fat feeding.


METHODS
Weaning rats were fed a low-fat or a high-fat diet for 15 days.


METHODS
Energy balance and lipid partitioning in the whole animal. State 3 and state 4 oxygen consumption rates in whole skeletal muscle homogenate. State 3 and state 4 oxygen consumption rates, membrane potential and uncoupling effect of palmitate in subsarcolemmal and intermyofibrillar mitochondria from skeletal muscle.


RESULTS
Rats fed a high-fat diet showed an increased whole body lipid utilization. Skeletal muscle NAD-linked and lipid oxidative capacity significantly increased at the whole-tissue level, due to an increase in lipid oxidative capacity in subsarcolemmal and intermyofibrillar mitochondria and in NAD-linked activity only in intermyofibrillar ones. In addition, rats fed a high-fat diet showed an increase in the uncoupling effect of palmitate in both the mitochondrial populations.


CONCLUSIONS
In young rats fed a high-fat diet, skeletal muscle contributes to enhanced whole body lipid oxidation through an increased mitochondrial capacity to use lipids as metabolic fuels, associated with a decrease in energy coupling.
Iossa
S
S
Department of General and Environmental Physiology, University of Naples Federico II, Naples, Italy.
Mollica
M P
MP
Lionetti
L
L
Crescenzo
R
R
Botta
M
M
Liverini
G
G
D000821:Animal Feed; D000818:Animals; D000831:Animals, Newborn; D001823:Body Composition; D004041:Dietary Fats / Q000008:administration & dosage*; D002149:Energy Intake; D004734:Energy Metabolism / Q000187:drug effects; D050356:Lipid Metabolism; D008297:Male; D008931:Mitochondria, Muscle / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects*; D051381:Rats; D017208:Rats, Wistar
D004041:Dietary Fats