A method for intratracheal instillation in the rat

A method was developed to provide safe, rapid, and accurate intratracheal instillation of radionuclides into the rat lung. Rats were anesthetized with halothane and suspended vertically on an animal support stand with rubber bands attached to the incisor teeth, holding the mouth open. A speculum was inserted into the trachea and the radionuclide was injected from a syringe through tubing inserted through the tracheal speculum into the trachea. The amount of radionuclide retained in the lung varied by less than a factor of 2 within groups of rats observed 4 hr-20 da after employing this method of instillation. When a volume of 2 ml was instilled, the radionuclide distribution between the left and right lung was similar to that observed following incorporation by inhalation. Instillations of less than 2 ml showed unequal distribution of radionuclide between the right and left lung.