Fujimori Hiroyuki, Ozaki Kiyokazu, Matsuura Tetsuro, Matsushima Shuuichi, Narama Isao, Pan-Hou Hidemitsu
Department of Analytical Chemistry in Hygiene, Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan.
Biol Pharm Bull. 2004 Sep;27(9):1371-5. doi: 10.1248/bpb.27.1371.
To elucidate the pathophysiological significance of adenosine 3'-monophosphate (3'-AMP) forming enzyme in rats, the effect of iron lactate overloading on the enzyme activities and adenine nucleotide levels in the liver and spleen was examined. Sprague-Dawley rats were fed a diet supplemented with 0%, 0.625% or 5.0% of iron lactate for 4 weeks. Iron deposition was found in periportal hepatocytes, Kupffer cells and macrophages of red pulp of the spleen. No significant changes in hematological parameters were detected. Although serum alkaline phosphatase and inorganic phosphorus levels elevated slightly in the 5.0% group, activities of alanine aminotransferase and aspartate aminotransferase, and levels of serum urea nitrogen and creatinine were not changed significantly. The ATP levels in the liver and spleen of iron fed groups were significantly decreased, but adenosine 5'-diphosphate (ADP) and adenosine 5'-monophosphate (AMP) levels were within control levels. On the other hand, the levels of ATP, ADP and AMP in the erythrocytes without mitochondria were not suppressed by the iron lactate overloading. Free activity of 3'-AMP forming enzyme, one of ribonucleases (RNase), was not changed in the liver of iron-overloaded rat, and total amount of 3'-AMP and adenosine formed after the treatment of the crude enzyme(s) with p-chloromercuribenzensulfonic acid, a SH blocker of RNase inhibitors, was decreased dose-dependently. On the contrary, free activity of 3'-AMP forming enzyme was enhanced dose-dependently in the spleen of iron-overloaded rat but the total activity was not changed. However, the free and total 3'-AMP forming enzyme activities in the liver and spleen of iron-overloaded rats became equal at the dosage of 5.0% of iron lactate. The results obtained suggested that iron loading might induce significant decrease in hepatic and splenic ATP levels via malfunction of their mitochondria and might lead dissociation of RNase-RNase inhibitor complex to activate 3'-AMP forming enzyme in both tissues.
为阐明大鼠中3'-单磷酸腺苷（3'-AMP）形成酶的病理生理意义，研究了乳酸铁过载对肝脏和脾脏中该酶活性及腺嘌呤核苷酸水平的影响。将斯普拉格-道利大鼠喂食添加0%、0.625%或5.0%乳酸铁的饲料4周。在肝门周围肝细胞、库普弗细胞和脾脏红髓巨噬细胞中发现铁沉积。未检测到血液学参数的显著变化。虽然5.0%组血清碱性磷酸酶和无机磷水平略有升高，但丙氨酸转氨酶和天冬氨酸转氨酶活性以及血清尿素氮和肌酐水平无显著变化。喂食铁的组肝脏和脾脏中的ATP水平显著降低，但5'-二磷酸腺苷（ADP）和5'-单磷酸腺苷（AMP）水平在对照范围内。另一方面，无线粒体的红细胞中的ATP、ADP和AMP水平未被乳酸铁过载抑制。铁过载大鼠肝脏中核糖核酸酶（RNase）之一的3'-AMP形成酶的游离活性未改变，在用对氯汞苯磺酸（一种RNase抑制剂的SH阻断剂）处理粗酶后形成的3'-AMP和腺苷总量呈剂量依赖性降低。相反，铁过载大鼠脾脏中3'-AMP形成酶的游离活性呈剂量依赖性增强，但总活性未改变。然而，在乳酸铁剂量为5.0%时，铁过载大鼠肝脏和脾脏中3'-AMP形成酶的游离和总活性变得相等。所得结果表明，铁负荷可能通过其线粒体功能障碍导致肝脏和脾脏ATP水平显著降低，并可能导致RNase-RNase抑制剂复合物解离，从而激活两个组织中的3'-AMP形成酶。
