EFFECTS OF CHAIN-LENGTH AND TELLURIUM POSITION ON THE MYOCARDIAL UPTAKE OF TE-123M FATTY-ACIDS

Abstract

A series of 123mTe-labeled fatty acids was synthesized and studied in rats. In this series of compounds, the position of the 123mTe heteroatom was not as important as the total chain length, which dramatically affected the heart uptake. Five minutes after injection, significant heart uptake (1.7-2.3% of injected dose) was observed for agents with C15, C17 and C21 chain lengths, in which 123mTe replaced a methylene group in the 6, 9, 11 or 17 positions and the heart-to-blood ratios were high. An important observation was the prolonged retention of radioactivity for at least 1 h after injection. Agents with shorter C13 chain lengths, with 123mTe in the 6 or the 9 position, exhibited only low heart uptake (0.1-0.3% of injected dose).