Time course of discordant BMIPP and thallium uptake after ischemia and reperfusion in a rat model

Serial changes in fatty acid metabolism or use associated with acute ischemia and reperfusion were examined in rat hearts. Methods: Male Wistar rats were subjected to occlusion of the left coronary artery for 20 min followed by reperfusion. After release of the occlusion, groups of animals were allowed to recover for intervals of 20 min (n = 9), 1 d (n = 9), 3 d (n = 6), 7 d (n = 6), or 30 d (n = 6). Hearts were excised 15-20 min after injection of 0.74 MBq of ¹²⁵I-15-(p-iodophenyl)-3-R,S-methylpentadecanoic acid (BMIPP) and 14.8 MBq of ²⁰¹TI. One minute before resection, the left coronary artery was reoccluded and 185 MBq of ^99mTc-sestamibi were injected to document the area at risk. Triple-tracer autoradiography was performed to assess tracer uptake. Uptake ratios of BMIPP and ²⁰¹TI in the area at risk were calculated on the basis of the count density in the lesion divided by that in the normally perfused area. Results: ²⁰¹TI uptake did not change throughout the observation period (P = 0.25). In contrast, BMIPP uptake increased early in the acute phase (20 min and 1 d), decreased during the sub-acute phase (7 d), and subsequently recovered in the chronic phase (30 d). Conclusion: The present investigation clearly illustrated that BMIPP uptake is higher than ²⁰¹TI uptake in the acute phase, that BMIPP uptake is lower than ²⁰¹TI uptake in the subacute phase, and that BMIPP uptake and ²⁰¹TI uptake are similar in the chronic phase. These results yield data essential to the precise interpretation of BMIPP images.