ADVANTAGES AND LIMITATIONS OF EXPERIMENTAL-TECHNIQUES USED TO MEASURECARDIAC ENERGY-METABOLISM

The heart requires a constant supply of energy to sustain contractile function, which is supplied by hydrolysis of adenosine triphosphate de rived primarily from the metabolism of fatty acids and carbohydrates, Understanding how production of adenosine triphosphate is regulated in the heart ir; critical to an understanding of how alterations in ener gy metabolism contribute to the severity of cardiac disease, A number of techniques can be used to measure energy metabolism in the heart, T hey include biochemical measurement of metabolites and enzymes of inte rmediary metabolism, measurement of arteriovenous differences in carbo n substrate extraction by the heart, measurement of high-energy phosph ates with P-31 nuclear magnetic resonance, measurement of the rate of flux through the pathways of intermediary metabolism with C-14- and H- 3-labeled carbon substrates, measurement of tricarboxylic acid cycle a ctivity with C-13 nuclear magnetic resonance, and measurement of gluco se uptake and oxidative metabolism with positron emission tomography, Each of these techniques has advantages and limitations.