Influence of Temperature on the Absorption of Inhaled Bovine Serum Albumin through Isolated Rabbit Lungs

Abstract

Abstract

We examined the influence of temperature on the absorption of inhaled ¹²⁵I-bovine serum albumin (BSA) and ¹²⁵I^- into the pulmonary circulation in isolated rabbit lungs. The lungs were insufflated for 15 min with an aerosol containing either ¹²⁵I-BSA or Na ¹²⁵I. The inhaled dose was the amount deposited in the lungs distal to the main bronchi. Blood samples were obtained from the perfusion circuit for 4.5 hr following insufflation. When ¹²⁵I-BSA was inhaled, the ¹²⁵I appeared in the blood in trichloroacetic acid (TCA)-soluble and TCA-precipitable fractions. At 38°, the TCA-precipitable and TCA-soluble fractions appeared in the blood at rates of about 1.4 and 1.9% of the inhaled dose per hour, respectively. Cooling to 12° reduced these rates to 0.25 and 0.12% per hour, respectively. The initial rate of ¹²⁵I^- absorption was much more rapid (4%/min) and no temperature dependence was detected. These results indicate that the rates of absorption and breakdown of inhaled albumin were markedly temperature dependent, while the absorption of the low molecular weight ¹²⁵I was not.