Abstract
After i.v. infusion of endotoxin (Escherichia coli) into Sprague-Dawley rats, in the absence of airway manipulation, the absolute number of neutrophils in bronchoalveolar lavage (BAL) samples increased significantly 24 and 48 h after injection. This represented nearly a 24 h delay from the time that maximal numbers of neutrophils were seen in lung tissue and approximately an 18 h delay from the time that maximal numbers appeared in peripheral blood. After infusion of endotoxin the number of pulmonary alveolar macrophages (PAM) recoverable in BAL samples fell dramatically within 2 h and remained suppressed for at least 12 h. Thus, neutrophils are capable of migration into air spaces after aggregation in pulmonary capillaries in the absence of airway manipulative procedures or instillation of chemoattractants into air spaces; endotoxemia affected surface parameters of PAM in vivo that determine recoverability by BAL.