A Reliable Method for Intratracheal Instillation of Materials to the Entire Lung in Rats

Abstract

A novel method for intratracheal instillation of rats is described by which an operator can confidently administer a liquid sample into the tracheal lumen, with direct observation of the entrance to the trachea. To confirm its efficacy, indigo carmine was administered with or without air to investigate optimal conditions for exposure of the whole lung. After administration of 0.5 ml of indigo carmine and an equal volume of air simultaneously by intratracheal instillation, sections through the whole lung demonstrated positive staining with the dye. For histological examination, 0.5 ml of saline containing iron oxide followed by an equal volume of air was administered intratracheally. Iron particles were observed in the wall of bronchioles and alveolar macrophages of whole lung. The method allows reliable intratracheal administration to large numbers of rats within a short period and should, therefore, prove useful for assays of toxicity in the respiratory tract.