An isolated rabbit kidney preparation for use in organ preservation research

Abstract

An isolated rabbit kidney preparation has been developed principally for use as a laboratory assay to compare experimental renal preservation techniques. Perfusion was carried out at 37°C and an arterial pressure of 110 mm Hg using bloodless perfusates containing bovine serum albumin, dextran, hydroxyethyl starch, or Pluronic F108. Glomerular filtration rate and protein leakage were determined with each perfusate. It was found that low filtration rates and high degrees of protein leakage were obtained with perfusates containing either albumin, dextran, or a mixture of these colloids, but both pluronic and hydroxyethyl starch gave acceptable glomerular filtration rates and relatively low protein leakage. The pluronic perfusate was selected for further study. Isolated rabbit kidneys had a greatly reduced vascular resistance, and medullary flow was increased to a proportionally greater degree than cortical flow. The concentration gradient of Na+ normally found between cortex and medulla was lost, and this was associated with an inability of perfused kidneys to effect osmolal concentration of urine. Oxygen consumption was within the limits published for the organ in vivo, and during perfusion the total nucleotide content of renal tissue was well maintained, but there was a small decrease in the ATP/ADP ratio. Function improved steadily during the first hour of perfusion to give a GFR during the second hour that was close to the physiological norm. The fractional reabsorption of water, glucose, and sodium reached maxima of 63, 80, and 67%, respectively. Although the performance of the preparation is subphysiological, it is stable during the time required for the comparison of preserved kidneys and is reproducible. The preparation has already yielded valuable data in this field.