Palmitate-induced cardiac apoptosis is mediated through CPT-1 but not influenced by glucose and insulin.
To test the hypothesis that regulation of palmitate metabolism, through carnitine palmitoyl transferase-1 (CPT-1) or through alterations of glycolysis, was involved in the pathway of palmitate-mediated cell death, cardiomyocytes were cultured from 7-day-old chick embryos. Palmitate-induced cell death, assessed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, was enhanced by carnitine, a cofactor needed for palmitate transport into mitochondria via CPT-1. Carnitine co-incubation with palmitate significantly (P < 0.01) increased the amount of apoptotic cells, assessed by propidium iodine staining and fluorescent-activated cell sorting analysis compared with treatment with either palmitate or carnitine alone. The CPT-1 inhibitor oxfenicine significantly (P < 0.05) blocked the cell death induced by the combination of palmitate and carnitine. The short-chain saturated fatty acid capric acid (100 microM), which is not likely transported by CPT-1, did not significantly affect cell viability, whereas the C18 saturated fatty acid stearic (100 microM) significantly (P < 0.01) reduced cell viability and to a similar extent as palmitate. In contrast, there was no significant alteration of palmitate-induced cell death by cotreatment with 100 nM insulin + 2 g/l glucose or 1 mM lactate, which promote ATP generation by glycolysis rather than fatty acid oxidation. Fumonisin did not alter palmitate-induced cell death or apoptosis, suggesting that the effect of palmitate was not operative through increased ceramide synthesis. These results suggest that oxidation of palmitate through CPT-1 is involved in the production of apoptosis in cardiomyocytes.
Kong
Jennifer Y
JY
Division of Cardiology, Department of Medicine, University of British Columbia, Vancouver, British Columbia, Canada V5Z 3J5.
Rabkin
Simon W
SW
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002264:Carboxylic Acids / Q000494:pharmacology; D002331:Carnitine / Q000494:pharmacology; D002334:Carnitine O-Palmitoyltransferase / Q000378:metabolism*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D002642:Chick Embryo; D004247:DNA / Q000032:analysis; D003652:Decanoic Acids / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D037341:Fumonisins; D005947:Glucose / Q000494:pharmacology; D005998:Glycine / Q000031:analogs & derivatives* / Q000494:pharmacology; D006352:Heart Ventricles / Q000166:cytology / Q000201:enzymology; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D019344:Lactic Acid / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology* / Q000201:enzymology; D019308:Palmitic Acid / Q000494:pharmacology*
D002264:Carboxylic Acids; D003652:Decanoic Acids; D004791:Enzyme Inhibitors; D037341:Fumonisins; D007004:Hypoglycemic Agents; D007328:Insulin; D019308:Palmitic Acid; D019344:Lactic Acid; C056933:fumonisin B1; C031071:decanoic acid; C023010:4-hydroxyphenylglycine; D004247:DNA; D002334:Carnitine O-Palmitoyltransferase; D005947:Glucose; D002331:Carnitine; D005998:Glycine