Tellurium-labeled fatty-acid analogs: Relationship of heteroatom position to myocardial kinetics

Abstract

To determine the effects of tellurium-heteroatom position on myocardial fatty-acid kinetics, a series of tellurium Te 123m-labeled heptadecanoic-acid analogs (^123mTe-THDA) were evaluated in dogs. The left-anterior descending coronary artery was partially occluded, and ^123mTe-THDA labeled at either the 5, 6, 9, 10, 11, 12 or 13 position from the carboxyl group was administered intravenously. In 24 dogs, the ^123mTe activity in the ischemic and normal zones was monitored continuously for 3 h using miniature radiation detectors. There were no significant differences between the ischemic- and normal-wall ^123mTe clearance rates for any of the compounds. There was minimal fractional 3-h myocardial clearance for the ^123mTe-THDA labeled at the 5, 6, and 9 position (range of means, 0.02–0.05). There was significant clearance of ^123mTe-THDA labeled at the 11, 12, and 13 position (range of means, 0.37–0.44). The myocardial clearance of the ^123mTe-THDA labeled at the 10 position was intermediate between the two extremes. Thus, as the ^123mTe heteroatom is placed further from the carboxyl portion of the molecule, there is a progressive increase in the myocardial clearance. Selection of the heteroatom position should depend on whether initial fatty-acid distribution or subsequent clearance rates are being studied.