Oxidative metabolism in the myocardium in normal subjects during dobutamine infusion

To assess the biventricular response of the clearance rate of carbon-11 acetate as an index of myocardial oxidative metabolism to increase in work-load, dynamic positron emission tomography was performed at rest and during dobutamine infusion in 14 normal subjects. The clearance rate constant (Kmono) of the left ventricular (LV) myocardium increased during dobutamine infusion (0.112 +/- 0.020 min-1 vs 0.065 +/- 0.015 min-1 at rest) (P < 0.001) in proportion to the increase in the pressure-rate product. Kmono in the right ventricular (RV) myocardium also increased (0.080 +/- 0.018 min-1 vs 0.034 +/- 0.013 min-1 at rest) (P < 0.001), with an excellent correlation with the LV Kmono (r = 0.920). The fact that the increase in RV Kmono during dobutamine infusion was greater (158% +/- 81%) than that in LV Kmono (79% +/- 39%) (P < 0.005) indicates a greater increase in oxidative metabolism in the RV in response to inotropic stimulation in normal subjects.