Glowniak J V, Wilson R A, Joyce M E, Turner F E
Department of Nuclear Medicine, Veteran's Affairs Medical Center, Portland, Oregon 97207.
J Nucl Med. 1992 May;33(5):716-23.
Metaiodobenzylguanidine (MIBG) is a norepinephrine analog that can be used to study cardiac sympathetic innervation. Most of the kinetic data on MIBG, however, have been obtained in vitro from adrenal chromaffin cells. To elucidate MIBG cardiac kinetics in vivo, we measured the first-pass extraction fraction (EF) of MIBG in pig heart and lungs and determined the relationship between the cardiac EF and myocardial blood flow (MBF) before and after dipyridamole, cocaine and imipramine. The first-pass lung EF was 24% +/- 0.80% (mean +/- s.e.). The baseline cardiac EF of MIBG was 79% +/- 1.6%. With dipyridamole, MBF increase significantly and the EF fell (82% +/- 2.5% to 71% +/- 3.5% baseline compared to 0.03 mg/kg/min dipyridamole, p less than 0.001), indicating that the cardiac EF of MIBG is dependent on MBF. Cocaine infusion had no effect on MBF or EF. Imipramine caused a significant increase in the EF (72% +/- 3.5% versus 77% +/- 2.5%, baseline versus imipramine p = 0.032) without a change in MBF. In adrenal chromaffin cells, cocaine and imipramine decrease MIBG uptake, suggesting that adrenal chromaffin cells may be an inappropriate model for studying MIBG kinetics in cardiac sympathetic neurons.
间碘苄胍（MIBG）是一种去甲肾上腺素类似物，可用于研究心脏交感神经支配。然而，大多数关于MIBG的动力学数据是在体外从肾上腺嗜铬细胞中获得的。为了阐明MIBG在体内的心脏动力学，我们测量了猪心脏和肺中MIBG的首过提取分数（EF），并确定了潘生丁、可卡因和丙咪嗪给药前后心脏EF与心肌血流量（MBF）之间的关系。首过肺EF为24%±0.80%（平均值±标准误）。MIBG的基线心脏EF为79%±1.6%。使用潘生丁时，MBF显著增加而EF下降（与0.03mg/kg/min潘生丁相比，基线时为82%±2.5%，给药后降至71%±3.5%，p<0.001），表明MIBG的心脏EF依赖于MBF。输注可卡因对MBF或EF无影响。丙咪嗪使EF显著增加（基线时为72%±3.5%，丙咪嗪给药后为77%±2.5%，p = 0.032），而MBF无变化。在肾上腺嗜铬细胞中，可卡因和丙咪嗪会降低MIBG摄取，这表明肾上腺嗜铬细胞可能不是研究心脏交感神经元中MIBG动力学的合适模型。
