[Comparative studies of the cyclic AMP content and renewal of this nucleotide in thymic, splenic and lymph-node lymphocytes in adult rats].

Cyclic AMP (c-AMP) content and turnover were measured in pure preparations of lymphocytes obtained from thymus, spleen and lymph nodes in the Rat. The c-AMP content was determined by combining the methods of Krishna and of Thomson and Appleman, and its turnover was estimated from the activities of adenylcyclase and phosphodiesterase using 3H-adenine. The values, espressed per 10(8) cells, were the lowest for the thymus and the highest for the lymph nodes, while they were intermediary for the spleen. The differences in the c-AMP turnover between the three organs may be correlated with the extent of the mitotic activity of the corresponding lymphocytes, this activity being related inversely to the turnover of c-AMP.