Gibson R E, Eckelman W C, Vieras F, Reba R C
J Nucl Med. 1979 Aug;20(8):865-70.
The distribution of [3H]quinuclidinyl benzilate and its methiodide salt was determined in rat, guinea pig, and rabbit. Accumulation in the myocardium of up to 2% of the injected dose per gram of tissue was obtained with both compounds, providing heart-to-blood ratios of approximately 30 and heart-to-lung ratios of approximately 4. The accumulation in the heart was blocked (89%) by preinjection of atropine. The distribution of tritium in rabbit heart corresponds to the muscarinic receptor densities determined in vitro. Calculation of the theoretical maximum for the bound-to-free ratio, based on in-vitro equilibrium binding isotherms, resulted in ratios in reasonable agreement with the experimental results. Because of the high accumulation in the heart with low serum concentration, we conclude that the methiodide salt of quinuclidinyl benzilate represents an ideal parent structure for the design of a receptor-binding gamma-emitting radiopharmaceutical for imaging of the myocardium.
测定了大鼠、豚鼠和兔体内[3H]奎宁环基苯甲酸酯及其甲碘化物盐的分布情况。两种化合物在心肌中的蓄积量均可达每克组织注射剂量的2%，心脏与血液的比值约为30，心脏与肺的比值约为4。预先注射阿托品可使心脏中的蓄积量减少（89%）。兔心脏中氚的分布与体外测定的毒蕈碱受体密度相符。根据体外平衡结合等温线计算结合与游离比值的理论最大值，所得比值与实验结果合理相符。由于心脏中蓄积量高而血清浓度低，我们得出结论，奎宁环基苯甲酸酯甲碘化物盐是设计用于心肌成像的受体结合γ发射放射性药物的理想母体结构。
