Urine Production and Metabolism of Glucose and Lactic Acid in the Kidney During 36 Hours of Cooling and Perfusion with Diluted Plasma

Abstract

Six dog kidneys were cooled to 10°C and perfused for 36 hours in a perfusion machine with and without coupling the oxygenator. Diluted, human, microfiltered plasma was used as perfusate. With the technique employed and with a perfusion pressure of 90/60 mmHg, the perfusion could be kept constant at 125–150 ml/minute. The pH of the perfusate rose from 7.13 to 7.55 during the perfusion. The renal function was evaluated in vitro. The kidneys consumed oxygen, and the lactic acid concentration in the perfusate fell on the average 1.5 mM/36 hours, dependent on the oxygen tension. No certain change was demonstrable in the glucose concentration of the perfusate. The urine production was 100–200 ml/hour during the whole perfusion period. The urine was an ultrafiltrate with a maximum protein content of 3 g/1. A comparison of the composition of the perfusate and the urine suggested a minor resorption of sodium and water in the tubules. The composition of the urine, the small increase in the content of potassium and lactic acid dehydrogenase in the perfusate, and the fall in the lactic acid concentration suggest that the technique employed is applicable to long-term perfusion. Employment of an oxygenator seems to be of minor importance. The parameters used, especially the protein content in the urine, seem to be suitable for function tests during long-term perfusion and for testing perfusates and new perfusion techniques.