EXTRACELLULAR ASCORBIC-ACID IN LUNG

Of the ascorbic acid content of sliced rat lung, 50% was released from the tissue to the media within a few minutes by either washing or incubating the slices with Krebs-phosphate solution. Measurement of the lactate dehydrogenase and potassium content of the medium after incubating lung slices for 5 min showed that about 20% of the cells were damaged by slicing. Sephadex chromatography of tissue extracts prepared from washed lung slices showed that none of the ascorbic acid in these slices was bound to protein. Metabolic poisons depleted the ascorbic acid content of washed lung slices. Approximately, 57% of the lung ascorbic acid of guinea pigs that was supplemented with ascorbic acid and 78% of the lung ascorbic acid of ascorbic acid-deficient guinea pigs were found in the medium when lung slices from these animals were incubated with Krebs-phosphate solution. These results indicate the presence of an extracellular pool of ascorbic acid in lung which is maintained even during scurvy.