Importance of endogenous substrates for cultured adult rat cardiac myocytes

• Published in: Biochimica et biophysica acta Vol. 883; no. 3; pp. 531 - 541
• Main Authors: Piper, Hans M., Spahr, Rolf, Schweickhardt, Christa, Hunneman, Donald H., Probst, Irmelin
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.10.1986; Elsevier; North-Holland
• Subjects: Animals; Biological and medical sciences; Cell metabolism, cell oxidation; Cell physiology; Cells, Cultured; Diglycerides - metabolism; Endogenous substrate; Energy Metabolism; Fatty acid oxidation; Fatty Acids - metabolism; Female; Fundamental and applied biological sciences. Psychology; Hydrolysis; Lipid Metabolism; Molecular and cellular biology; Myocardium - metabolism; Oxidation-Reduction; Pyruvate Dehydrogenase Complex - metabolism; Rat cardiomyocyte; Rats; Rats, Inbred Strains; Triacylglycerol; Triglycerides - metabolism; Fatty acid oxidation; Endogenous substrate; Triacylglycerol; Rat cardiomyocyte; Hepes; Heart; Cell culture; Vertebrata; Mammalia; Rat; Rodentia; Lipids; Oxidation; Metabolism; Triglyceride; Fatty acids; Heart cell
• ISSN: 0304-4165; 0006-3002; 1872-8006; 1878-2434
• DOI: 10.1016/0304-4165(86)90294-1

In Ca-tolerant adult cardiomyocytes the contribution of endogenous substrates (glycogen, tri- and diacylglycerol) to oxidative substrate metabolism was investigated. After 4 h in culture medium (M 199 plus 4% fetal calf serum) the cellular triacylglycerol content is 3.6-fold higher than in fresh myocardium and reflects the free fatty acid composition of the medium. When triacylglycerol is degraded, all long-chain fatty acids are hydrolysed at equal rates. In these quiescent cells, the activity of pyruvate dehydrogenase is low (10% of full activity, in Tyrode solution with 5 mM glucose). Up to 30% of full pyruvate dehydrogenase activity, the contribution of non-lipid substrates (glycogen, glucose, lactate and pyruvate) to oxidative energy production is correlated to pyruvate dehydrogenase activity. At 5 mM mediumconcentration, glucose, lactate and pyruvate share in energy production the proportions of 15, 36 and 50%, whereas endogenous lipolysis accounts for 78, 61 and 46%. It is concluded that these quiescent cardiomyocytes represent cardiac metabolism in a basal state in which the preference for fatty acids, especially from endogenous lipids, is very pronounced. The utilization of endogenous substrates therefore has to be considered in all studies investigating the oxidative metabolism of these isolated cells.