Effects of palmitoyl carnitine and related metabolites on the avian Ca(2+)-ATPase and Ca2+ release channel.
1. In birds, prolonged cold exposure induces the development of a non-shivering thermogenesis (NST) of muscular origin that may result from an increase in ATP-dependent cycling of Ca2+ between the sarcoplasmic reticulum (SR) and the cytosol. 2. Because fatty acids are thought to play a significant role in NST, we investigated the effects of palmitic acid and related metabolites on skeletal SR Ca2+ uptake and release in ducklings. 3. Ca(2+)-ATPase activity, 45Ca2+ release and [3H]ryanodine-binding measurements indicated that palmitic acid was without effect on the Ca(2+)-ATPase and Ca2+ release channel. Palmitoyl carnitine and palmitoyl coenzyme A inhibited the Ca(2+)-ATPase at concentrations > 20 microM whereas both activated the Ca2+ release channel at concentrations < or = 20 microM in a dose-dependent manner. 4. Palmitoyl carnitine stimulated [3H]ryanodine binding to skeletal but not cardiac SR vesicles. Induction of 45Ca2+ release was observed with long-chain (C > or = 14) but not with short-chain acyl carnitines (C < or = 12). 5. Long-chain acyl carnitines accumulated significantly in duckling skeletal muscle during cold acclimation. Accordingly, these results suggest that long-chain acyl metabolites may modulate SR Ca2+ cycling and its associated thermogenesis in vivo.
Dumonteil
E
E
Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599-7260.
Barré
H
H
Meissner
G
G
D000818:Animals; D001833:Body Temperature Regulation / Q000502:physiology; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000032:analysis / Q000378:metabolism / Q000502:physiology*; D003080:Cold Temperature; D004372:Ducks / Q000502:physiology*; D008297:Male; D018482:Muscle, Skeletal / Q000737:chemistry / Q000201:enzymology / Q000378:metabolism; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000494:pharmacology; D010171:Palmitoyl Coenzyme A / Q000494:pharmacology; D010172:Palmitoylcarnitine / Q000494:pharmacology*; D012433:Ryanodine / Q000378:metabolism; D014316:Tritium
D015220:Calcium Channels; D010169:Palmitic Acids; D014316:Tritium; D012433:Ryanodine; D010171:Palmitoyl Coenzyme A; D010172:Palmitoylcarnitine; D019308:Palmitic Acid; D000252:Calcium-Transporting ATPases; D002118:Calcium