American Journal of Clinical Nutrition, Vol 8, 131-136, Copyright © 1960 by The American Society for Clinical Nutrition, Inc.

Transport of Amino Acids Into and Across Cells

¹ From the Department of Biological Chemistry, The University of Michigan, Ann Arbor, Michigan

The question of whether or not transport across the intestinal mucosa or similar barriers can be studied in simpler forms has been considered. We have shown that cells can be arranged to form a membrane able to concentrate amino acids from one and into the other of two phases separated by the membrane. This was achieved by adding pyridoxal or pyridoxal phosphate to the first phase, or by adding an excess of potassium ion to the second phase. The characteristics for the transport across the cells were exactly similar to those for accumulation into the cells.

These results show that the concentrative process for cells produces elevated levels of free amino acids, and is able to simulate the behavior of a secretory tissue. They further show that the attributes found for the transport into or out of cells are significant for transmucosal transport. Accordingly, these attributes have been summarized, and possible ways in which active transport may take place have been considered.