A 13 C NMR double-labeling method to quantitate local myocardial O 2 consumption using frozen tissue samples

• Published in: American journal of physiology. Heart and circulatory physiology 1999-10, Vol.277 (4), p.H1630-H1640
• Main Authors: van Beek, Johannes H G M, van Mil, Harald G J, King, Richard B, de Kanter, Frans J J, Alders, David J C, Bussemaker, Joli
• Format: Article
• Language: English
• ISSN: 0363-6135; 1522-1539
• DOI: 10.1152/ajpheart.1999.277.4.H1630

Measurement of local myocardial O consumption (V˙o ) 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 V˙o using small frozen myocardial samples, suitable for determiningV˙o profiles. In 26 isolated rabbit hearts, 1.5 mmol/l [2- C]acetate was infused for 4 min, followed by 1.5 min of [1,2- C]acetate. The left ventricular (LV) free wall was then quickly frozen. High-resolution C-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 localV˙o was calculated. The C-derivedV˙o in the LV free wall was linearly related to "gold standard"V˙o from coronary venous O 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 V˙o was 1.52 ± 0.19 (SE, significantly >1, P< 0.025). Local myocardialV˙o can now be quantitated with this new C method to determine profiles of aerobic energy metabolism.