Metabolism of beta-methyl[1-11C]heptadecanoic acid in canine myocardium.
To assess the contributions of metabolism to CO2 and back-diffusion of nonmetabolized tracer to total clearance of beta-methyl[1-11C]heptadecanoic acid ([1-11C]BMHDA) from myocardium and its distribution into lipid pools, 10-15 mCi of [1-11C]BMHDA were rapidly infused into the circumflex coronary artery of seven open-chest dogs. Externally detected clearance of myocardial 11C-activity was protracted (t1/2 = 41 +/- 18 min) with over 50% of extracted tracer retained in tissue after 20 min. Efflux of extracted [1-11C]BMHDA between 5 and 20 min was comprised of both 11CO2 (16.5 +/- 15.2%) and nonmetabolized [11C]BMHDA (24.6 +/- 11.5%). At 20 min, 11C-activity in lipid was distributed primarily between triglyceride (47 +/- 16% of total) and phospholipid (39 +/- 17%) pools. Partial oxidation to 11CO2 and partitioning into more than one lipid pool are likely to hinder evaluation of fatty acid metabolism based on residue detection of [1-11C]BMHDA with tomography.
Cardiovascular Division, Washington University School of Medicine, St. Louis, MO 63110.
D R
DR
Abendschein
K A
KA
Fox
H D
HD
Ambos
B E
BE
Sobel
S R
SR
Bergmann
D000818:Animals; D002250:Carbon Radioisotopes; D003327:Coronary Disease / Q000378:metabolism; D004285:Dogs; D005227:Fatty Acids / Q000097:blood / Q000378:metabolism*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D014280:Triglycerides / Q000378:metabolism
D002250:Carbon Radioisotopes; D005227:Fatty Acids; D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; C033637:3-methylheptadecanoic acid