EXPERIMENTAL STUDIES ON THE PRESERVATION OF THE CANINE KIDNEY

Histochemical Enzyme Activities and Mitochondrial Respiration

Abstract

The canine kidneys were preserved at a low temperature (2°-4°C) in a hyperbaric oxygen chamber (3ATM) up to 168 hours. These kidneys had been removed few minutes after autotransplantation and examined for histochemical enzyme activities and mitochondrial respiration. The following results were obtained.
1. Histological findings (H. E. stain)
Although great individual differences are seen in the histological findings, the changes such as dissociation of the epithelium of the proximal tubuli begin to appear at about 24 hours of preservation. Generally hyperemia of interstitial capillaries, especially those in the renal medulla, is intense. The interstitium is somewhat edematous. At about 72 hours of preservation, dilatation and hyperemia of the glomerular arterioles are markedly intensified and the presence of vascular disturbance can be inferred. However, even at 168 hours of kidney preservation some healthy nephrons persist.
2. Histochemical enzyme activities
Enzyme activities of LAP, SDH, ATP-ase, β-G, Al-p-ase and Acid-p-ase were studied. There was a great variation in enzyme activities in each specimens. However, almost no change was noted in ATP-ase. Other histochemical enzyme activities decreased in parallel with degeneration of the renal tubular epithelium. As the time of preservation lengthens, the areas of decreasing activities progress in extent. However, even at 168 hours some nephrons retain enzyme activities and some healthy nephrons persist. Changes during this period are continuous and it is difficult to judge at what degree of disappearance the viability of the whole kidneic is irretrievably lost.
3. Electron microscopic findings of the mitochondrial fractions
Mitochondria were separated by the Hogeboom and Schneider method and confirmed through the electron microscope. However, even mitochondria obtained from a healthy control kidney showed marked swelling and rupture of their outer membranes. No characteristic differences in parallel with the preservation time were seen from the morphological findings by the electron microscope.
4. Respiratory control function of the mitochondria
The average values for the ADP/0 ratio and RCI (Respiratory Control Index) for the healthy control kidneys were 1.246 and 1.99 respectively. The ADP/0 ratio and RCI of mitochondria of preserved kidneys was calculated on a percentage basis based on the healthy control kidneys. Up to 24 hours, excluding those in which Indigo carmine excretion was not observed within 10 minutes, the ADP/0 ratio was more than 80%, and RCI was at the 80% level. In the 48 hours preserved kidney two groups were established, one group with the ADP/0 ratio maintained at 70-80% and the other group with a decrease and eventual disappearance being noted. The number in the two groups was the same, being 37.8% on the average. RCI was 70% on the average when unmeasurable cases were made to represent 0. As for the kidneys preserved more than 72 hours, the ADP/0 ratio was 0 in all cases and it was inferred that oxidative phosphorylation was disturbed. In the 168 hours preserved kidney the respiratory control function was extinguished. From the above findings it can be accepted that preservation of the kidney at 2°-4°C under 3ATM oxygen for 48 hours is the limit of viability. Preservation for more than 72 hours is extremely difficult.