EFFECTS OF ALLOXAN AND HISTAMINE ON PERMEABILITY OF PULMONARY ALVEOLOCAPILLARY BARRIER TO ALBUMIN

1. [131I]albumin transport from alveolus to perfusion fluid was evaluated in an isolated dog lung lobe preparation perfused at constant pressure with homologous plasma. The alveoli were filled with a 1:1 mixture of Ringer—Tyrode solution and plasma. 2. For twenty‐three lung lobes, an average control permeability coefficient of the alveolocapillary membrane for albumin was found to be 1·9 × 10−9 cm/sec with a range of (0·3–5·5) × 10−9 cm/sec. 3. Alloxan in concentrations of 0·22–2·50 mg/ml. perfusate was observed to increase the alveolocapillary membrane permeability to [131I]albumin with a positive correlation between dose and effect. The larger doses of alloxan increased the permeability by a factor of ten or more. 4. Glutathione (GSH), administered intravascularly 2 min before alloxan in an 8:1 molar ratio of GSH:alloxan, delayed the onset of the permeability increase due to alloxan by 40–60 min but did not influence the maximum increase in permeability. 5. Histamine administered intravascularly in concentrations from 0·02 to 0·50 μg/ml. perfusate had no significant effect on the alveolocapillary membrane permeability to [131I]albumin. © 1969 The Physiological Society