Absorption of sulfate ions in the rat lung

To investigate the absorption of 35S-sulfate ions from the rat lung in the presence of sodium, ammonium, and chloride ions, 0.1 ml of isotonic sucrose solution containing the salts was instilled via a tracheal cannula into anesthetized animals. After various times the lungs were removed and assayed for 35S-radioactivity. Sulfate ion absorption was found to be nonsaturable and proportional to the concentration of sulfate ion, with a t 1/2 =34.5 minutes. Ammonium ions enhanced the absorption of sulfate ions by 10.8 +/- 3.1% and chloride ions decreased the absorption of sulfate ions by 6.6 +/- 3.0%.