Absorption of albumin from alveoli of perfused dog lung

Abstract

An iodinated albumin solution was instilled into the isolated perfused dog lung through a bronchial catheter. During the 5-hr period following instillation, 6.4% of the iodinated albumin dose was absorbed from the lung into the pulmonary perfusion blood. Fifty-seven percent of the absorbed radioactivity passed through an Amberlite resin column indicating that absorption occurred as large protein molecules. Fractionation of the plasma protein-bound radioactivity on a diethylaminoethyl-cellulose column demonstrated that absorption of the iodinated albumin from the lung had been predominantly as intact albumin molecules. Since the pulmonary lymphatic drainage was interrupted in the perfused lung, absorption of the albumin must have been directly from the alveoli into the pulmonary capillary blood. It is concluded that in the isolated lung the primary mechanism for removal of albumin from the pulmonary alveoli is slow absorption of intact albumin directly into the pulmonary blood.