Myocardial Triacylglycerol Metabolism: The Role of ‘Competition’ Between Different Substrates

Triacylglycerols have the potential to supply significant fatty acids for ATP production by the myocardium, yet at present the exact contribution of triglyceridederived fatty acid to the energy economy of the myocardium is unresolved. Chylomicrons and very-low-density lipoproteins both add to energy production but the degree of provision may be related to particle size of individual lipoproteins and is less affected by changes in the prevailing concentration of triacylglycerols than non-esterified fatty acids. The myocardium may represent a significant ‘sink’ for both plasma fatty acids and triacylglycerols as the heart possesses a high capillary density and high capillary surface area and may therefore represent a tissue for which ‘spillover’ of the products of lipolysis may make a limited donation to plasma non-esterified fatty acid, and triacylglycerol-derived fatty acids are partitioned towards β-oxidation to a greater extent than tissue-esterified lipids.