The modification of sodium excretion after abdominal irradiation. A dose-effect relationship study in the rat.

Whole-body counting of radiosodium disappearance in the rat enabled us to evaluate the disturbance induced in sodium excretion after gamma abdominal irradiation at different doses (500, 750, 1000, 1250 and 1500 R). The observed modification is consistent with a sodium excretion loss depending on the dose. Two indices, the relative excretion rate (theta) and the recovery time (deltat), completely define the radio-induced modification and make feasible the quantitative assessment of its dependence on the dose. The development of the dose-response relationship established for each of these indices leads us to conclude that the reduction in the sodium-excretion rate, which can be related to a defect in sodium intake, is a linear function of the dose, while the time needed to recover the pre-irradiation sodium excretion rate increases exponentially with the dose.