The metabolism of 15-p-[123I]-iodophenylpentadecanoic acid in a surgically induced canine model of regional ischemia.

The purpose of this study was to examine the longitudinal effect of gradual coronary occlusion on regional myocardial metabolism of 15-p-123I-iodophenylpentadecanoic acid [( 123I]IPPA). Adult dogs were imaged using [123I]IPPA and planar gamma imaging. A thoracotomy was performed and an ameroid constrictor of appropriate size permanently positioned on the left anterior descending coronary artery. The dogs were imaged after injection of 3-5 mCi [123I]IPPA at various times over a 2-week period. With imaging on days 7 and 14, the dogs were paced at a rate of 185. Time-activity curves were generated and t1/2 values calculated using monoexponential curve fitting. Results indicate a significant increase in t1/2 between control and 14 days after surgery in the apical wall (29 +/- 7 to 53 +/- 18 min; P less than 0.05). Although there was also an increased t1/2 in the lateral wall, this was not significant (27 +/- 8 to 78 +/- 99 min; P greater than 0.05). There was no significant change in t1/2 in the septal wall (27 +/- 9 to 33 +/- 8 min; P greater than 0.05). We conclude that [123I]IPPA is a useful indicator of developing myocardial ischemia.