A (13) C NMR double-labeling method to quantitate local myocardial O (2) consumption using frozen tissue samples
van Beek, J.H.; van Mil, H.G.; King, R.B.; de Kanter, F.J.; Alders, D.J.; Bussemaker, J.
American Journal of Physiology 277(4): H1630-H1640
1999
ISSN/ISBN: 0002-9513 PMID: 10516204 Document Number: 507134
Measurement of local myocardial O2 consumption (VO2) has been problematic but is needed to investigate the heterogeneity of aerobic metabolism. The goal of the present investigation was to develop a method to measure local VO2 using small frozen myocardial samples, suitable for determining VO2 profiles. In 26 isolated rabbit hearts, 1.5 mmol/l acetate. The left ventricular (LV) free wall was then quickly frozen. High-resolution 13C-NMR spectra were measured from extracts taken from 2- to 3-mm thick transmural layer samples. The multiplet intensities of glutamate were analyzed with a computer model allowing simultaneous estimation of the absolute flux through the tricarboxylic acid cycle and the fractional contribution of acetate to acetyl CoA formation from which local O2 was calculated. The 13C-derived VO2 in the LV free wall was linearly related to "gold standard" VO2 from coronary venous O2 electrode measurements in the same region (r = 0.932, n = 22, P < 0.0001, slope 1.05) for control and lowered metabolic rates. The ratio of subendocardial to subepicardial VO2 was 1.52 ± 0.19 (SE, significantly >1, P < 0.025). Local myocardial VO2 can now be quantitated with this new 13C method to determine profiles of aerobic energy metabolism. Reprinted by permission of the publisher.