Metabolic reserve in normal myocardium assessed by positron emission tomography with C-11 palmitate.
Positron emission tomography (PET) with C-11 palmitate has been used in estimating the myocardial utilization of free fatty acid. To assess the metabolic reserve in normal subjects, a PET study was performed at control and during dobutamine infusion at 2 hour intervals in 5 normal subjects. Following monoexponential curve fitting of the time activity curve of the myocardium, the clearance half time (min) and residual fraction (%) were calculated as indices of beta-oxidation of free fatty acid. A significant increase in the heart rate and systolic blood pressure were observed during dobutamine infusion (65 +/- 5 vs 100 +/- 29 bpm, p less than 0.05 and 119 +/- 12 vs 144 +/- 16 mmHg, p less than 0.01, respectively). The clearance half time and the residual fraction were significantly decreased (23.4 +/- 2.6 vs 15.8 +/- 2.3 min and 67.0 +/- 2.5 vs 58.6 +/- 4.0%, P less than 0.05, each). When the left ventricular myocardium was divided into 4 segments, these indices were similar at control and uniformly decreased without regional differences during dobutamine infusion. These data suggest that beta-oxidation of free fatty acid may be uniformly increased in the left ventricular myocardium in relation to the increase in cardiac work in normal subjects. PET with C-11 palmitate at control and during dobutamine infusion is considered to be promising in assessing metabolic reserve in the myocardium.
Tamaki
N
N
Department of Nuclear Medicine, Kyoto University Faculty of Medicine, Japan.
Kawamoto
M
M
Takahashi
N
N
Yonekura
Y
Y
Magata
Y
Y
Nohara
R
R
Kambara
H
H
Kawai
C
C
Konishi
J
J
D000328:Adult; D000368:Aged; D002250:Carbon Radioisotopes; D004280:Dobutamine; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D006321:Heart / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010168:Palmitates; D012016:Reference Values; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D005230:Fatty Acids, Nonesterified; D010168:Palmitates; D004280:Dobutamine