Shevchenko T S, Kobyalko V O
Radiats Biol Radioecol. 2015 Jul-Aug;55(4):411-9.
The activity of the cyclic adenosine-3,5-monophosphate (cAMP) in lymphocytes and platelets of sheep has been studied for 15 days after animal exposure to total external γ-radiation at a dose of 4 Gy (LD50/30). The basal and E1 stimulated activity of adenylate cyclase and phosphodiesterase activity were determined by the thinlayer chromatography technique, and the cAMP content was determined using RIA-kits with 125J. Modification was revealed in the cAMP system functioning in the cell populations studied from the first day following radiation exposure. In particular, the basal adenylate cyclase activity in lymphocytes increased 1.7-4.3 times at all study dates, and stimulated enzyme activity increased on days 1-7, 21-8.8-fold compared to the initial data. Platelets showed increase in the basal adenylate cyclase activity on days I and 7, 2.7 and 35 times, and stimulated activity at the same times--9 and 5.7 times, respectively. The adenylate cyclase stimulation coefficient in lymphocytes raised 1.8 and 2.3 times on days 1 and 5, respectively, on day 7 it corresponded to the initial data and on days 10-15 it dropped below the control. However in platelets, this parameter did not have significant differences from the initial data. The phosphodiesterase activity in lymphocytes increased 3-fold on day 3, 2.4-fold on day 7, and in platelets it practically remained at the control level. The cAMP content in lymphocytes dropped within the first 12 hours and on day 3, 2.71 and 2.38 times, respectively, whereas in platelets it decreased 3.08 times within 12 hours and increased 1.91 times on day.3. At other times the cAMP content in lymphocytes and platelets did not differ from the initial data. The results suggest that the identified modification of cAMP system activity in lymphocytes and platelets in various periods after exposure of animals is based on different mechanisms. In the early period, alteration in the enzyme activity of cAMP system and cAMP content is caused by radiation effects on cytoplasmic membrane of cells circulating in the peripheral blood of animals. In the later periods, the recorded variations in the cAMP system activity are defined by the prevalence in the blood of more resistant to radiation damage cell subpopulation with an enhanced activity of cAMP enzymes and cAMP concentration corresponding to unexposed animals.
在绵羊接受4 Gy（LD50/30）的全身外照射γ辐射后15天，研究了其淋巴细胞和血小板中环磷酸腺苷（cAMP）的活性。采用薄层色谱技术测定腺苷酸环化酶的基础活性和E1刺激活性以及磷酸二酯酶活性，使用含125I的放射免疫分析试剂盒测定cAMP含量。从辐射暴露后的第一天起，就发现所研究的细胞群体中cAMP系统的功能发生了改变。具体而言，在所有研究日期，淋巴细胞中的基础腺苷酸环化酶活性增加了1.7 - 4.3倍，在第1 - 7天，刺激后的酶活性增加，与初始数据相比增加了8.8倍。血小板在第1天和第7天的基础腺苷酸环化酶活性分别增加了2.7倍和3.5倍，同时刺激后的活性分别增加了9倍和5.7倍。淋巴细胞中腺苷酸环化酶的刺激系数在第1天和第5天分别提高了1.8倍和2.3倍，第7天与初始数据相当，在第10 - 15天则降至对照水平以下。然而，在血小板中，该参数与初始数据没有显著差异。淋巴细胞中的磷酸二酯酶活性在第3天增加了3倍，在第7天增加了2.4倍，而血小板中的磷酸二酯酶活性实际上保持在对照水平。淋巴细胞中的cAMP含量在最初12小时内以及第3天分别下降了2.71倍和2.38倍，而血小板中的cAMP含量在12小时内下降了3.08倍，在第3天增加了1.91倍。在其他时间，淋巴细胞和血小板中的cAMP含量与初始数据没有差异。结果表明，动物暴露后不同时期淋巴细胞和血小板中cAMP系统活性的上述改变是基于不同机制。在早期，cAMP系统的酶活性和cAMP含量的改变是由辐射对动物外周血中循环细胞的细胞质膜的影响引起的。在后期，cAMP系统活性的记录变化是由血液中对辐射损伤更具抗性的细胞亚群占优势所决定的，这些细胞亚群的cAMP酶活性增强，cAMP浓度与未暴露动物相当。
