[Incorporation of a 131-iodine-deoxycytidine monophosphate protamine complex into the DNA of tumor-bearing rats following partial synchronization with hydroxyurea].

The incorporation of 131-Iodo-deoxyuridine in rat tumours can be increased by partial synchronisation with hydroxyurea. The reported investigation was carried out to determine whether the incorporation could be further increased by using a basic 131-Iodo-deoxycytidine-monophosphate-protamine complex as a depot of Iodo-deoxyuridine. It was shown that the incorporation observed after synchronisation could be increased by using this complex (non-synchronized tumours 1,46% retention, synchronized tumours 2,28% retention; measured 4 hour after the final injection of hydroxyurea) whereas in a control group injected with 131-Iodo-deoxycytidine-monophosphate alone, only a small increase was observed. The large increase in activity in the liver and in the spleen (liver: non-synchronized 2,76%, synchronized 2,79% retention; spleen: non-synchronized 3,00, synchronized 3,80% retention; measured 4 hours after final injection of hydroxyurea) which is observed after injection of the 131-Iodo-deoxycytidine-monophosphate-protamine complex renders it unsuitable for use in the scintigraphic detection of tumours. 131-Iodo-deoxyuridine is shown to be more suitable for this purpose.