Myocardial Uptake of Labeled Oleic and Linoleic Acids

Oleic acid labeled with $sup 14$Ca, ($sup 14$C-OA) or $sup 131$I ($sup 131$I-OA) and $sup 131$I- labeled linoleic acid ($sup 131$I-LOA) were administered intravenously to rats and tissue distribution studies completed at various time intervals from 5 to 60 min. Tissue distribution of $sup 131$I- labeled oleic acid or linoleic acid was also studied in dogs at 5- and 30-min time intervals after intravenous administration of the tracer dose. There were distinct differences in the patterns of tissue distribution between $sup 14$C-OA: $sup 131$I-OA, and $sup 131$I-LOA. Radioactivity concentration in the myocardium was the highest at all time intervals in the rats given $sup 131$I-OA only. In dogs, the myocardial uptake of $sup 131$I-OA was significantly higher than the radioactivity in the blood or other tissues at 30 min after injection. The disappearance rates of $sup 131$I-OA and $sup 131$I-LOA were almost identical but myocardial concentration of $sup 131$I-LOA at 30 min after the dose in the dog was half that of $sup 131$I-OA whereas $sup 131$I-LOA liver concentration was higher than that of $sup 131$-OA. Since the concentrations of the formulated $sup 131$I-OA in the blood and in the myocardium are both highest at the earlier intervals, it shouldmore » be difficult to detect myocardial ischemia or infarction with $sup 131$I-OA scanning. (auth)« less