Uptake of 125I-iododeoxyuridine in mouse organs during deuteration of body water: Evidence for a thymus-specific effect

Abstract

The effects of body water deuteration on mammalian DNA synthesis in vivo during the deuterium equilibration period in the body were studied. Young adult mice were given 15% or 30% D 2O in the drinking water for 4, 10 or 21 days. Control mice were given distilled water. Eighteen hours prior to sacrifice, 125IUdR, a conveniently monitored synthetic analogue of the DNA precursor thymidine, was injected intravenously. Although neither radioiodine activity of the total body nor body weight varied significantly among the three groups, thymic radioactivity per g tissue was significantly lower in mice given 30% D 2O and, to a lesser extent, in mice given 15% D 2O than in the control group. In contrast, intestine and hemopoietic bone marrow displayed minor changes in 125IUdR incorporation. This reduction of 125IUdR incorporation is discussed in relation to the particular importance of thymidine reutilization in the thymus.