Increase in the process of accumulation of amino acids in carrot slices with prolonged aerobic washing

Abstract

The increase in salt-stimulated respiration and of the active accumulation of amino acids in slices of carrot has been investigated during washing by circulation aerobically and anaerobically. Salt-stimulated respiration and amino acid accumulation which increase on aerobic circulation can be reversed by anaerobic circulation of carrot slices. When the rate of dinitrophenol-sensitive accumulation of D- and L-amino acids is compared in freshly cut slices and in aerobically circulated slices, it has been found that the increased rate of accumulation after circulation is much greater with the D-isomer than with the L-isomer. High concentrations (30-70 mM) of free amino acids are found in the tissue fluid, and extracts of the tissue containing these amino acids have been shown to compete with other externally supplied amino acids for the accumulation process. It has been concluded that the increase in salt-stimulated respiration, and in the accumulation of amino acids when the tissue is aerobically circulated, is related to the removal during this process of endogenous substances from the cytoplasm or carrier sites or from both. The results obtained are discussed in relation to the increase in the active accumulation of inorganic ions and of the so called malonate-sensitive respiration.