title: Deposition of particles in the lungs of infant and adult rats after direct intratracheal administration.
abstract: The study of neonatal pulmonary defense mechanisms has been limited by difficulty in administering foreign material into the lungs of newborn animals. We have developed and standardized a simple method for the intratracheal instillation of particles into the distal airways of newborn rats. We used this method to compare intrapulmonary particle deposition in neonatal and adult rats. We instilled 51Cr-labeled microspheres (11 microns diameter) by direct intratracheal inoculation into the lungs of neonatal (< 2- or 19-h-old) and adult (6-week-old) Sprague-Dawley rats. Immediately after microsphere instillation, the lobar distribution of the particles was analyzed by scintillation counting. The anatomic location of the particles was determined by autoradiography. The instilled microspheres reached all lobes in both lungs of neonatal and adult rats. The pattern of distribution in the right lung was nearly identical in the neonatal and adult rats. In the left lung, however, particles deposited preferentially in the cranial lobe in neonates but in the caudal lobe of adult rats. Analysis of the location of particle deposition in the lungs indicated that 64% +/- 6.85 (n = 4) reached the distal airways in the neonates vs. 85% +/- 3.3 (n = 6) in the adults, whereas the remainder deposited in the conducting airways. This method provides an effective means of delivering particles into distal airspaces of neonatal rats and can be used to study pulmonary defense mechanisms in newborn animals.
authors.affiliation: Medical Research Service of the Seattle Veterans Affairs Medical Center, WA, USA.
authors.forename: J T
authors.initials: JT
authors.lastname: Ruzinski
authors.forename: S J
authors.initials: SJ
authors.lastname: Skerrett
authors.forename: E Y
authors.initials: EY
authors.lastname: Chi
authors.forename: T R
authors.initials: TR
authors.lastname: Martin
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001345:Autoradiography; D001980:Bronchi / Q000033:anatomy & histology; D002860:Chromium Radioisotopes; D005260:Female; D008168:Lung / Q000033:anatomy & histology; D008297:Male; D008863:Microspheres; D011247:Pregnancy; D011650:Pulmonary Alveoli / Q000033:anatomy & histology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013047:Specific Pathogen-Free Organisms; D013997:Time Factors; D014132:Trachea
chemical_list: D002860:Chromium Radioisotopes