Positron Emission Tomography Analysis of [1-11C]Acetate Kinetics in Short-term Hibernating Myocardium

R. Schulz, C. Kappeler, H. Coenen, A. Bockisch, G. Heusch
1998 Circulation  
Background-Modeling of the time-[1-11 C]acetate activity curve assumes a constant concentration of labeled tricarboxylic acid cycle intermediates and associated metabolites, such as glutamate and aspartate, which may, however, decrease in short-term hibernating myocardium. Methods and Results-In 12 anesthetized pigs, [1-11 C]acetate was injected as a bolus into the cannulated left anterior descending coronary artery during normoperfusion, inotropic stimulation, and early (5 to 45 minutes) and
more » ... olonged ischemia (60 to 90 minutes). Regional myocardial oxygen consumption (MV O 2 , microliters per minute per gram) was measured, and the absence of necrosis was verified by triphenyl tetrazolium chloride staining. Inotropic stimulation increased MV O 2 from 52.5Ϯ7.4 to 195.4Ϯ36.2 (meanϮSD) and the rate constant (k mono , minutes Ϫ1 ) of [1-11 C]acetate clearance from 0.094Ϯ0.018 to 0.322Ϯ0.076. During early ischemia, MV O 2 and k mono were decreased to 24.3Ϯ8.5 and 0.061Ϯ0.011, respectively. K mono closely correlated to MV O 2 during normoperfusion, inotropic stimulation, and early ischemia. In short-term hibernating myocardium, however, at an unchanged MV O 2 , k mono increased toward control values (0.080Ϯ0.014). Myocardial glutamate and aspartate concentrations (biopsies) decreased to 47Ϯ26% and 77Ϯ18%; the peak count rate decreased to 66Ϯ22% of its respective control value. After correction for the decreases in glutamate and aspartate or in peak count rate, k mono was again decreased (0.050Ϯ0.016 or 0.052Ϯ0.014, respectively), and a close relationship to MV O 2 was restored. Conclusions-K mono correlates to MV O 2 in short-term hibernating myocardium when the decreases in aspartate and glutamate or in peak count rate are considered. (Circulation. 1998;97:1009-1016.)
doi:10.1161/01.cir.97.10.1009 pmid:9529270 fatcat:ly7c2mnlmjgbtk3gde6757cegy