Metabolism in the hypothermically perfused dog kidney. Utilization and production of amino acids

The uptake and utilization of amino acids in dog kidneys during hypothermic perfusion were studied. 21 kidneys were perfused in a Gambro perfusion machine for 6 days with perfusates based on human albumin with and without addition of 17 L-amino acids. Net glucose uptake by the kidney was lower during perfusion with amino acids in the perfusate than during perfusion without amino acids. A decrease in specific activity of labelled glucose was found during perfusion with amino acids in the perfusate indicating a considerable gluconeogenesis which could explain the difference in net glucose uptake. A higher uptake of fatty acids by the kidney was found during perfusion with amino acids in the perfusate than during perfusion without amino acids. In perfusion without amino acids the concentration in the perfusate of almost all amino acids and ammonia increased and thus a net release of nitrogen was found indicating degradation of protein. In perfusion with amino acids in the perfusate a considerable uptake and release of amino acids by the kidney were found. The most pronounced uptake was registered for glutamine, proline and glycine. The most pronounced release was registered for glutamate, alanine and ammonia. During perfusion with amino acids in the medium, the uptake and release of nitrogen were balanced as distinguished from perfusion without amino acids in the perfusate.