AGRICULTURAL BIOLOGY, 2015, V. 50, ¹ 4, pp. 495-502 ISSN 2412-0324 (English ed. Online) (SEL’SKOKHOZYAISTVENNAYA BIOLOGIYA) ISSN 0131-6397 (Russian ed. Print) ISSN 2313-4836 (Russian ed. Online) doi: 10.15389/agrobiology.2015.4.495rus doi: 10.15389/agrobiology.2015.4.495eng EFFECTS OF EXTERNAL -RADIATION ON ADENYLATE CYCLASE ACTIVITY IN SHEEP BLOOD CELLS T.S. SHEVCHENKO, I.V. KONOPLEVA Federal Agency of Scientific Organizations, 109 km, Kievskoe sh., Obninsk, Kaluga Province, 239032 Russia, e-mail riar@obninsk.org, Shevchenkotatyana@yandex.ru A b s t r a c t In the mechanisms of action of various adverse factors on mammals a special part is assigned to the regulatory systems. <...> The main regulatory system of cellular metabolism is the cAMP system. <...> Exposure of animals to external -radiation results in the modification of different biochemical processes in cells. <...> In studying diversified intercellular disorders after irradiation it is, therefore, necessary to assess functioning of the cAMP system and its key enzyme, the adenylate cyclase. <...> Note that the data published on the effect of -irradiation are mainly obtained with laboratory animals which are significantly different from farmed animals in the body features, whereas the effect in highly productive animals is of special interest. <...> We studied an influence of -irradiation on cAMP in Tsygai sheep for the first time and showed a cAMP modification both in the lymphocytes susceptible to radiation and in the thrombocytes which are relatively resistant. <...> In this paper the data are shown on the basal and prostaglandin E1 stimulated activity of adenylate cyclase in radiosensitive blood cells of sheep exposed to total external -radiation at a dose of 4 Gy (LD50/30) for 15 days. <...> From the first day after exposure, changes have been revealed in all activity components of this enzyme in the lymphocytes and thrombocytes of sheep. <...> The lymphocytes showed a 1.7-4.3-fold increase in the basal adenylate cyclase activity on days 1-15 and 1.3-3.8-fold increase in the stimulated activity on days 1-10. <...> In thrombocytes the basal activity of adenylate cyclase increased 2.7 and 3.5 times on days 1 and 7, respectively, and the prostaglandin E1 stimulated activity of adenylate cyclase grew 6.9 and 5.7 times on days 1 and 7 after exposure, respectively. <...> This suggests that i) modification of adenylate cyclase activity is caused by postradiation alteration of the structural-functional <...>