Kitos T E, Tyrrell D L
Department of Medical Microbiology and Infectious Diseases, University of Alberta, Edmonton, Canada.
Biochem Pharmacol. 1995 May 11;49(9):1291-302. doi: 10.1016/0006-2952(95)00052-2.
The intracellular fate of the potent duck hepatitis B virus (DHBV) inhibitor 2,6-diaminopurine 2',3'-dideoxyriboside (ddDAPR), its deamination product 2',3'-dideoxyguanosine (ddG), and the less effective DHBV-inhibitor 2',3'-dideoxycytidine (ddC) was investigated in duck hepatocyte primary cultures. After a 1-min exposure of [3H]ddDAPR to duck blood, 95% of the compound was converted to ddG. Similarly, [3H]ddDAPR was converted rapidly to ddG in duck hepatocyte primary cultures, with ddG exhibiting resistance to further catabolism. The major pathway of ddG utilization in these cells was phosphorylation, yielding a concentration of 2.1 and 1.9 microM total ddG nucleotides after 5 and 26 hr, respectively, of exposure to 4 microM ddG. Removal of exogenous ddG led to a rapid (T1/2 = 1.6 hr) decrease in the total intracellular ddG nucleotide pools. Duck hepatocytes treated with 4 microM ddC exhibited a time-dependent accumulation of ddC nucleotides, culminating in a maximum intracellular total ddC nucleotide concentration of 1.4 microM after 24-26 hr. The intracellular total ddC nucleotide level decreased with a T1/2 of 4.4 hr following the removal of exogenous ddC. The formation of ddC nucleotides was reduced in the presence of excess 2'-dideoxycytidine implicating deoxycytidine kinase in the initial step of ddC phosphorylation. A 25-fold excess of 2'-deoxycytidine had no effect on ddG phosphorylation in duck hepatocytes. However, a 92% inhibition of ddG nucleotide formation occurred in duck hepatocytes treated for 5 hr with 4 microM [3H]dG + 100 microM adenosine in the presence of the adenosine deaminase inhibitor 2'-deoxycoformycin, suggesting that, in these cells, adenosine kinase is involved in the ddG phosphorylation process.
在鸭原代肝细胞培养物中研究了强效鸭乙型肝炎病毒（DHBV）抑制剂2,6-二氨基嘌呤2',3'-二脱氧核糖核苷（ddDAPR）、其脱氨基产物2',3'-二脱氧鸟苷（ddG）以及效果较差的DHBV抑制剂2',3'-二脱氧胞苷（ddC）在细胞内的命运。用[³H]ddDAPR处理鸭血液1分钟后，95%的该化合物转化为ddG。同样，在鸭原代肝细胞培养物中[³H]ddDAPR迅速转化为ddG，且ddG对进一步分解代谢具有抗性。这些细胞中ddG利用的主要途径是磷酸化，在暴露于4μM ddG 5小时和26小时后，总ddG核苷酸浓度分别为2.1μM和1.9μM。去除外源性ddG导致细胞内总ddG核苷酸池迅速（半衰期 = 1.6小时）减少。用4μM ddC处理的鸭肝细胞表现出ddC核苷酸的时间依赖性积累，在24 - 26小时后细胞内总ddC核苷酸浓度最高达到1.4μM。去除外源性ddC后，细胞内总ddC核苷酸水平以4.4小时的半衰期下降。在过量2'-脱氧胞苷存在的情况下，ddC核苷酸的形成减少，这表明脱氧胞苷激酶参与了ddC磷酸化的初始步骤。25倍过量的2'-脱氧胞苷对鸭肝细胞中ddG的磷酸化没有影响。然而，在腺苷脱氨酶抑制剂2'-脱氧助间型霉素存在的情况下，用4μM [³H]dG + 100μM腺苷处理鸭肝细胞5小时，ddG核苷酸形成受到92%的抑制，这表明在这些细胞中，腺苷激酶参与了ddG磷酸化过程。
