Department of Diagnostic Imaging and Nuclear Medicine, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo, 162-8666, Japan.
Ann Nucl Med. 2011 Oct;25(8):560-5. doi: 10.1007/s12149-011-0510-2. Epub 2011 Jul 6.
123I-beta-methyl iodophenyl pentadecanoic acid (BMIPP) can visualize myocardial fatty acid metabolism and has extensive potential for diagnosing cardiac diseases such as acute coronary syndrome in the clinical setting. Increased BMIPP uptake with decreased perfusion occasionally occurs under acute reperfusion ischemia and the kinetics of BMIPP remain unclear. The present study uses the isolated rat heart model to measure kinetic changes in BMIPP under acute reperfusion ischemia.
Male Wistar rats were allotted to normal control (NG), mild (MG) and severe (SG) ischemia groups. The hearts were perfused according to the Langendorff method at a constant flow rate, and BMIPP wash-in and wash-out were studied. No-flow ischemia was applied for 15 and 30 min to the MG and SG groups, followed immediately by the wash-in and wash-out study. Whole heart radioactivity was determined using an external gamma detector throughout the experiment. Rates of myocardial uptake (K1, mL/min) and clearance (k2, min(-1)) were generated using a compartmental model analysis. The same procedures and protocols were performed using (99m)Tc-sestamibi (MIBI) as a perfusion study.
Perfusion pressure significantly increased and mean heart rate significantly decreased in the severe ischemia group (heart rate: 244 ± 76, 304 ± 105 and 94 ± 140 bpm; perfusion pressure: 67 ± 13, 101 ± 31 and 160 ± 84 mmHg for NG, MG and SG, respectively). MIBI-K1 significantly decreased, whereas BMIPP-K1 increased in the MG and SG groups (MIBI-K1: 3.45 ± 1.10, 1.95 ± 0.82, and 1.05 ± 0.13 mL/min; BMIPP-K (1): 3.06 ± 0.88, 3.91 ± 0.87, and 4.94 ± 1.51 mL/min for NG, MG and SG, respectively) with an inverse relationship to the severity of ischemia. MIBI-k2 increased markedly in severe ischemia (NG vs. MG: p < 0.05), whereas BMIPP-k2 did not change in the ischemic groups (MIBI-k2: 0.00072 ± 0.0011, 0.00038 ± 0.00076 and 0.043 ± 0.033; BMIPP-k2: 0.0056 ± 0.0028, 0.0029 ± 0.0010 and 0.0037 ± 0.0022 min(-1) for NG, MG and SG, respectively).
Myocardial BMIPP uptake increased immediately upon reperfusion after no-flow ischemia, and was inversely related to the severity of ischemia. The increased uptake was not due to reduced clearance, but to accelerated extraction.
123I-β-甲基碘代苯戊酸（BMIPP）可用于可视化心肌脂肪酸代谢，在临床环境中对诊断急性冠状动脉综合征等心脏疾病具有广泛的应用潜力。在急性再灌注缺血时，偶尔会出现 BMIPP 摄取增加而灌注减少的情况，但其动力学仍不清楚。本研究使用离体大鼠心脏模型来测量急性再灌注缺血下 BMIPP 的动力学变化。
雄性 Wistar 大鼠被分为正常对照组（NG）、轻度缺血组（MG）和重度缺血组（SG）。心脏按 Langendorff 法以恒定流速灌注，研究 BMIPP 的摄取和洗脱。MG 和 SG 组分别进行 15 分钟和 30 分钟无血流缺血，然后立即进行摄取和洗脱研究。整个实验过程中，使用外部伽马探测器测定全心放射性。使用房室模型分析生成心肌摄取率（K1，mL/min）和清除率（k2，min-1）。使用（99m）Tc-甲氧基异丁基异腈（MIBI）作为灌注研究进行相同的程序和方案。
重度缺血组的灌注压显著升高，平均心率显著降低（心率：244±76、304±105 和 94±140 bpm；灌注压：67±13、101±31 和 160±84 mmHg 分别为 NG、MG 和 SG）。MIBI-K1 显著降低，而 MG 和 SG 组的 BMIPP-K1 增加（MIBI-K1：3.45±1.10、1.95±0.82 和 1.05±0.13 mL/min；BMIPP-K1：3.06±0.88、3.91±0.87 和 4.94±1.51 mL/min 分别为 NG、MG 和 SG），与缺血程度呈负相关。严重缺血时 MIBI-k2 显著增加（NG 与 MG 相比：p<0.05），而缺血组 BMIPP-k2 无变化（MIBI-k2：0.00072±0.0011、0.00038±0.00076 和 0.043±0.033；BMIPP-k2：0.0056±0.0028、0.0029±0.0010 和 0.0037±0.0022 min-1 分别为 NG、MG 和 SG）。
无血流缺血后再灌注即刻心肌 BMIPP 摄取增加，与缺血程度呈负相关。这种摄取的增加不是由于清除率降低，而是由于提取加速。
