Deposition and retention of cerium-141 in lung and local lymph nodes of rats after intratracheal injection of cerium-141 dioxide

Cerium-141 dioxide was administered intratracheally to rats by a single injection. Tested animals were killed at different intervals within 120 days after injection. Deposition and retention of 141Ce in the lung, tracheal and local lymph nodes (including cervical paratacheal, mediastinal and thoracic trachcobronchial lymph nodes) were evaluated by means of autoradiographic technique or γ-radioactivity measurement. The distribution of 141Ce in lymph nodes was quite heterogeneous at the three different levels. The highest concentration in the regional lymph nodes was in thoracic tracheobronchial ones. The concentration of 141Ce also varied in different lymph nodes in the same region. And even in the same lymph node, a heterogeneous spatial distribution of 141Ce was found, with the activity mainly limited in the medulla and paracortical zone. Maximum activity of local lymph nodes was observed 30-61 days after injection. In that time the deposited fraction of 141Ce in the local lymph nodes built up about 2 x 10-3 of the injected activity. Heterogeneous distribution of 141Ce was also observed in the lung. According to autoradiographic observation, the retention of 141Ce in lung was quite low 95 days after injection