Lysosomal enzyme release in hypothermically perfused dog kidneys

Lack of Cathepsin D in the Renal Proximal Tubular Cells Resulted in Increased Sensitivity against Renal Ischemia/Reperfusion Injury

Cathepsin D is one of the major lysosomal aspartic proteases that is essential for the normal functioning of the autophagy-lysosomal system. In the kidney, cathepsin D is enriched in renal proximal tubular epithelial cells, and its levels increase during acute kidney injury. To investigate how cathepsin D-deficiency impacts renal proximal tubular cells, we employed a conditional knockout CtsD^flox/−; Spink3^Cre mouse. Immunohistochemical analyses using anti-cathepsin D antibody revealed that cathepsin D was significantly decreased in tubular epithelial cells of the cortico-medullary region, mainly in renal proximal tubular cells of this mouse. Cathepsin D-deficient renal proximal tubular cells showed an increase of microtubule-associated protein light chain 3 (LC3; a marker for autophagosome/autolysosome)-signals and an accumulation of abnormal autophagic structures. Renal ischemia/reperfusion injury resulted in an increase of early kidney injury marker, Kidney injury molecule 1 (Kim-1), in the cathepsin D-deficient renal tubular epithelial cells of the CtsD^flox/−; Spink3^Cre mouse. Inflammation marker was also increased in the cortico-medullary region of the CtsD^flox/−; Spink3^Cre mouse. Our results indicated that lack of cathepsin D in the renal tubular epithelial cells led to an increase of sensitivity against ischemia/reperfusion injury.

Hypoxia/hypercapnia prevents iron-dependent cold injuries in cord blood stem and progenitor cells

BACKGROUND

Cold-induced cell injuries are associated with an increase in the cellular labile iron pool (LIP) followed by lipid peroxidation and alteration of mitochondrial function, which lead to cell death. Recently, we showed that incubation in a hypoxic/hypercapnic (HH) gas mixture improved the survival of a population of cord blood hematopoietic progenitors and CD34⁺ hematopoietic progenitor and stem cells in severe hypothermia. To explain the underlying mechanism, here we test if this HH-induced cytoprotection in cold conditions is associated with the level of LIP and lysosome stability.

METHODS

Cord blood CD34⁺ cells were incubated in air (20% O₂/0.05% CO₂) or in the hypoxic (5% O₂)/hypercapnic (9% CO₂) atmosphere for 7days at 4°C and analyzed.

RESULTS

Incubation in HH condition maintained the day 0 (D-0) level of LIP detected using a bleomycin-dependent method. This was associated with preservation of lysosome integrity and a higher cell survival. Conversely, in the air condition LIP was significantly increased. Also, the presence of a moderate concentration of iron chelator deferoximine improves the conservation of total CD34⁺ cells and committed progenitors in air condition. Pre-treatment of CD34⁺ cells with the lysomotropic agent imidazole induces significant decrease in the lysosomal stability and in all conditions. This is associated with an important decrease of survival of conserved cells and an increase in the cellular LIP level.

DISCUSSION

Our study showed that HH gas mixture cytoprotection during hypothermia maintains lysosome stability, which enables preservation of the cellular chelatable iron in the physiological ranges. These findings suggest a way to optimize cell conservation without freezing.

Effects of thermal stress on the activity of selected lysosomal enzymes in blood of experienced and novice winter swimmers

BACKGROUND

The aim of this study was to determine the effects of exposure to cold and heat on the activity of selected lysosomal enzymes as well as on the activity of the protease inhibitor, which are all considered to be markers of cellular damage.

MATERIAL

Two groups of healthy volunteers were included in the study. The first group consisted of experienced winter swimmers who practiced bathing in ice-cold water once a week, while the other group was comprised of persons who had never taken part in winter swimming before. During the experiment all the participants bathed in a river with a water temperature of 0 °C. The same volunteers were later subjected to a sauna bath at an air temperature of 85 °C.

METHODS

The activity of cathepsin D, alpha-1-antitrypsin, arylsulphatase and acid phosphatase was measured in the participant's blood serum.

RESULTS

After exposure to cold water no changes in the parameters studied could be found. However, after the sauna an increase in the activity of arylsulphatase and alfa-1-antitrypsin accompanied by a decrease of cathepsin D activity could be observed.

CONCLUSIONS

Winter swimming seems to have no effect on the activity of the lysosomal enzymes. By contrast, an increase of certain lysosomal enzymes after the sauna suggests that it may be deleterious to the lysosomal membranes. Furthermore it seems that regular winter swimming combined with sauna, according to hormesis theory, induces some adaptive response.

Iron and oxidative stress in cold-initiated necrotic death of rat hepatocyte

Iron chelators and antioxidants have been shown to prevent hypothermia-induced apoptosis in hepatocytes. This study examined whether iron chelation and antioxidants could also prevent hypothermia-induced necrosis. Isolated rat hepatocytes were incubated at 4 degrees C for 6 hours and then rewarmed at 37 degrees C for 18 hours with or without the iron chelator deferoxamine and a selection of antioxidants. There was no evidence of increased cell death or adenosine triphosphate depletion during hypothermic incubation. After hypothermia and rewarming, the majority of rat hepatocytes died of necrosis as indicated by the absence of DNA fragmentation, caspase 3 activity, and apoptotic bodies. Cell death was significantly reduced if deferoxamine or a selection of antioxidants were present during hypothermia and rewarming. Deferoxamine was more effective in preventing cell death when added prior to hypothermia, indicating cell death processes were likely initiated during hypothermia.

Oxidative stress causes a decline in lysosomal integrity during hypothermic incubation of rat hepatocytes

Oxidative stress during cold preservation has been identified as a significant cause of cell injury but the process by which injury occurs is poorly understood. We examined loss of lysosomal integrity as a possible cause of cell injury during extended cold storage of isolated rat hepatocytes. After 21 h of hypothermia, there was a marked decline in lysosomal integrity, which was correlated with an increase in lipid peroxidation. When lipid peroxidation was prevented with the antioxidant Trolox (a vitamin E analog) or the iron chelator desferrioxamine, lysosomal integrity was preserved. In contrast, increasing lysosomal iron with ferric chloride caused an increase in lipid peroxidation and decreased lysosomal integrity. Loss of lysosomal integrity during cold preservation in this experimental model was consistent with iron-initiated oxidative stress. The progressive loss of lysosomal integrity during hypothermic incubation has the potential to affect liver function after transplantation.

Hypothermic perfusion preservation: the future of organ preservation revisited?

Hypothermic perfusion preservation (HPP) was an integral step in the development of early clinical transplantation programmes, and considerable progress was made in understanding the basic principles underlying the technique. In subsequent years, the development of better preservation solutions for cold hypoxic storage, along with pragmatic choices made on grounds of costs and logistics, saw a fall in the application of HPP. More recently, the acute shortage of suitable organ donors and the inevitable pressure to use organs from sub-optimal (or expanded criteria) donors, has forced a re-evaluation of HPP, and the development of a new generation of HPP machines and associated perfusion solutions. This review sets out the historical development of HPP across the range of organs in which the method was originally investigated, describes the biological benefits and drawbacks associated with HPP, and sets out the most recent literature on the topic (including comments on the interest in use of higher temperatures in organ perfusion).

NOS: the underlying mechanism preserving vascular integrity and during ex vivo warm kidney perfusion

Research involving metabolically active and functioning organs, maintained ex vivo in culture-like conditions, could provide numerous opportunities for medical innovations and research. We report successful perfusion of isolated canine and human kidneys ex vivo at near physiologic temperature for 48 h. During the perfusions parameters of metabolism and function remained stable. Nitric oxide synthase (NOS) was identified as the underlying mechanism preserving vascular integrity. Most importantly, when the canine kidneys were reimplanted there was immediate normal renal function. This report highlights the potential significance of whole organ culture using a warm temperature ex vivo perfusion and discusses medical applications that could be developed.

The use of ischaemic vessels as prostheses or tissue engineering scaffolds after cryopreservation

OBJECTIVE

to evaluate the condition of organ donor arteries subjected to prolonged cold-ischaemia followed by cryopreservation, for their possible use as vascular grafts.

MATERIALS AND METHODS

fresh specimens of human iliac artery from organ donors were used as controls. These arteries were divided into two portions, one of which was cryopreserved in an automated freezer. A further group of arteries was immersed in Wisconsin solution and kept for 4 days at 4 degrees C (cold-ischaemia). After this period, the arteries were also cut into two, and one of these portions was cryopreserved. All the cryopreserved arterial segments were stored for a month and then subjected to automated gradual thawing. The thawed specimens were evaluated by light microscopy, scanning and transmission electron microscopy, immunohistochemical analysis (MMPs, elastin, CD31, von Willebrand factor) and the in situ detection of fragmented DNA (TUNEL method).

RESULTS

the most marked changes induced by cryopreservation were partial vessel deendothelialisation and morphological changes in cells of the intima that were in the process of detachment. No significant changes were observed in the medial layer, other than discrete elastic fibre fragmentation. Following cold-ischaemia, the endothelium was the most affected layer, with large denuded areas and exposure of the fibroelastic layer. Increased MMP-2 expression was also noted after cold-ischaemia. When subjected to both cold-ischaemia and cryopreservation, a large proportion of endothelial cells showed positivity for the TUNEL technique, however, no significant difference was observed between the ischaemic and the ischaemic/cryopreserved specimens.

CONCLUSIONS

prolonged cold-ischaemia causes some additional damage to the arterial wall compared to cryopreservation alone. However, the structural component of the ischaemic vessel remains in a condition that is suitable for subsequent cryopreservation and use as a vessel substitute or a scaffold for tissue engineering.

Alpha-1-proteinase inhibitor prolongs small intestinal graft preservation and survival

Organ preservation solutions currently used for cold storage of human donor organs are less effective in preserving small intestinal grafts than other organ grafts. The maximal safe period of cold preservation for human small intestinal graft is only about 6 hours. The pathology of preserved and reperfused small intestinal grafts is characterized by mucosal autolysis and sloughing. The authors speculated that the preservation/reperfusion injury results from a proteinase/proteinase-inhibitor imbalance in the graft that favors tissue degradation. This study evaluates whether the addition of an alpha-1-proteinase inhibitor (alpha-1-PI) to the preservation solution can improve graft survival after small bowel transplantation. Forty small intestinal grafts (20 cm long) were harvested from Lewis rats. The grafts were divided randomly into three groups and were preserved in one of the following solutions: normal saline (NS) (n = 10), alpha-1-PI (25 mg/mL; n = 20), or proteinase-free bovine serum albumin (BSA) (25 mg/mL; n = 10). After 12-hour cold storage in the respective solutions, the grafts were transplanted orthotopically into syngeneic recipients. Full-thickness graft biopsies were performed before and 1 hour after revascularization. The effectiveness of preservation was judged by graft histopathology and recipient survival. Histological studies showed that there was less mucosal autolysis and sloughing of the grafts in the alpha-1-Pl group than in the other two groups. All recipients in the NS and BSA groups died of graft failure within 7 days (NS: median, 4 days; range, 2 to 5 days; BSA: median, 6 days; range, 4 to 7). However, 60% (12 of 20) of the recipients in the alpha-1-PI group survived more than 90 days (median, > 90 days; range, 4 to > 90 days; P < .005 v NS or BSA groups, log-rank method). These data suggest that the inclusion of alpha-1-PI in the preservation solution may enhance graft integrity and improve the surgical outcome after small bowel transplantation.

Effect of cold storage on tissue and cellular glutathione

One of the mechanisms thought to cause injury in preserved organs is the formation of oxygen free radicals. The cell is protected from oxidative stress by many defense mechanisms. A major defense mechanism involves glutathione and glutathione-dependent enzymes. During organ preservation by simple cold storage the loss of glutathione may sensitize the organ to free radical damage after transplantation. In this study we show that glutathione is depleted from the rabbit liver, kidney, and heart cold-stored (5 degrees C) for up to 72 h in the UW solution without glutathione. In the first 24 h kidney glutathione decreased to 84 +/- 3% of control values, liver glutathione decreased to 49 +/- 3% of control values, and heart glutathione decreased to 73 +/- 3% of control values. After 48 h of storage the kidney and liver lost an additional 30 and 20%, respectively, whereas heart glutathione changed very little. By 72 h all three organs had lost more than 50% of the glutathione found in freshly obtained tissue. To determine if glutathione added to the UW solution can effectively prevent this loss of glutathione during preservation, hepatocytes were cold-stored for up to 72 h in a preservation solution with and without glutathione. We found that adding glutathione to the preservation solution slowed the rate of loss of glutathione from the cells. These data suggest that at hypothermia the cell may be permeable to GSH. Methods to suppress the loss of glutathione during preservation of organs may be an important factor in suppressing oxygen free radical injury.

Protection from nonfreezing cold injury by quinacrine, a phospholipase inhibitor

A recent study from our laboratory indicated additional tissue injury during rewarming of a cooled rabbit leg. Oxygen-derived free radicals were believed to play a role in such "rewarming injury." Since free radicals may attack membrane phospholipids, we analyzed the phospholipid composition in the leg tissue during cooling and rewarming. Our results indicated significant breakdown of membrane phospholipids, particularly phosphatidylcholine and phosphatidylethanolamine, with a corresponding accumulation of lysophosphatidylcholine and nonesterified fatty acids. Quinacrine, a phospholipase inhibitor, was able to preserve membrane phospholipids during rewarming of the cooled leg. Rewarming of cooled tissue was also accompanied by additional tissue injury, as evidenced by the increased release of lactic acid dehydrogenase and creatine kinase, as well as enhanced lipid peroxidation, as evidenced by increased malonaldehyde formation. Quinacrine reduced the release of these intracellular enzymes and decreased lipid peroxidation, suggesting its efficacy as a therapeutic agent against hypothermic injury.

Intracellular iron redistribution. An important determinant of reperfusion damage to rabbit kidneys

These studies were designed to examine the possible role of low molecular weight intracellular iron chelates (desferrioxamine-available (DFX-A) iron) in the damage which occurs during cold storage and subsequent reperfusion of kidneys. The level of DFX-A iron increased significantly (P less than 0.005) in the cortex of rabbit kidneys rendered cold ischaemic (CI) for 24 hr and the amount of iron available for DFX chelation increased significantly (P less than 0.05) in both the cortex and medulla of kidneys stored for 48 or 72 hr compared with fresh non-ischaemic controls. During ex vivo reperfusion of the organs with an oxygenated asanguinous perfusate, DFX-A iron returned rapidly to pre-ischaemic levels in 24 hr CI kidneys, but remained elevated following 48 and 72 hr CI (P less than 0.05 compared with 24 hr CI kidneys after 5 min reperfusion), returning to control levels only after 30 min reperfusion. There was no concurrent increase in total iron levels, indicating that a redistribution of iron to more accessible pools had occurred within the tissue. We suggest that decompartmentalization of intracellular iron during ischaemia and raised DFX-A iron levels over an extended period during subsequent reperfusion are responsible for increased catalysis of oxygen-derived free radical-mediated lipid peroxidation, and are an important factor in the deterioration of physiological function observed in rabbit kidneys following extended periods of cold storage.

Hypothermic preservation of hepatocytes. I. Role of cell swelling

Hepatocytes from isolated rat livers were hypothermically incubated (5 degrees C) in an oxygenated environment with continuous shaking (to simulate organ perfusion preservation). The incubation solution was either a tissue culture medium (L-15), an organ preservation perfusate (UW gluconate), or a simple cold-storage solution used for organ preservation (UW lactobionate). Hepatocyte viability was assessed from the release of lactate dehydrogenase (LDH) into the incubation medium. Cell swelling (due to the uptake of water) was also measured. Within 24 hr, hepatocytes hypothermically stored in each of the three incubation solutions became swollen (30 to 40% water gain) and lost a significant amount of LDH (as much as 60%). The addition of polyethylene glycol (PEG; relative molecular mass 8000; 5 g%) to the solutions suppressed cell swelling and allowed the incubated hepatocytes to remain relatively well preserved (30% LDH release) for as long as 120 hr. Adding either dextran (relative molecular mass 10,000 to 78,000; 5 g%) or saccharides (100 mmol/liter) instead of PEG neither prevented cell swelling nor prevented the cells from dying. The results of this study suggest (i) there is a direct correlation (r = 0.873) between hypothermia-induced cell swelling and cell death (i.e., the suppression of cell swelling prevents cell death); (ii) the mechanism by which PEG prevents cell swelling (and thus maintains cell viability) is not related to the osmotic or oncotic properties of the molecule but instead is apparently related to some unknown interaction between PEG and the cell, an interaction that provides stability during hypothermic incubation; and (iii) hypothermia-induced cell swelling must be prevented if isolated hepatocytes are to be used as a model for studying the mechanism by which cell damage occurs during hypothermic organ preservation. By eliminating cell death due to cell swelling, the biochemical mechanisms of cell death can be studied.

Hypothermic perfusion of rabbit livers: effect of perfusate composition (Ca and lactobionate) on enzyme release and tissue swelling

Rabbit livers were preserved by continuous hypothermic (5 degrees C) perfusion at a flow rate of 1 ml/min-1 g-1 for as long as 72 hr. Cell swelling (total tissue water, TTW) and the rate at which intracellular enzymes were released into the perfusate were measured. Livers perfused with a simple NaCl-based solution containing hydroxyethyl starch as a colloid released relatively large amounts of aspartate aminotransferase (AST, 442 +/- 224 u/liter-1 100 g-1) and lactic dehydrogenase (LDH, 1580 +/- 688 u/liter-1 100 g-1) into the perfusate during 72 hr of perfusion. The addition of Ca (0.5 mmol/liter) to the perfusate reduced the leakage of enzymes into the perfusate (AST, 70 +/- 30 u; LDH, 450 +/- 50 u) and reduced cell swelling (TTW, 3.1 kg/kg dry mass vs 4.4 kg/kg dry mass without added Ca). But the use of a higher concentration of Ca (1.5 mmol/liter) caused membrane damage (AST, 4000 +/- 1500 u; LDH, 10,000 +/- 2222 u) and increased cell swelling (TTW, 3.7 kg/kg dry mass). The release of intracellular enzymes caused by continuous perfusion with a chloride-based perfusate also could be reduced by replacing the chloride with lactobionate (AST, 100 +/- 30 u; LDH, 400 +/- 100 u, at 72 hr). In the lactobionate-containing perfusate, the addition of Ca (0.5 or 1.5 mmol/liter) did not alter the rate at which intracellular enzymes were released. There was no tissue swelling after 72 hr of preservation with the lactobionate-containing perfusate, and the TTW (2.1 kg/kg dry mass) was similar to the TTW of freshly harvested rabbit livers.(ABSTRACT TRUNCATED AT 250 WORDS)

Viability assays in organ preservation

Assays to determine the viability of preserved organs ideally must meet two important requirements: (i) in the clinical environment, they should allow the surgeon to determine if an organ will be viable when it is transplanted (this needs to be done in a noninvasive, nondestructive manner, and currently no such assay exists), and (ii) in the research environment, they should aid in the development of improved methods of organ preservation. Currently, however, the only reliable means of assessing viability is actual transplantation. Many conventional biochemical and physiological techniques have been used to describe the mechanism of preservation-induced injury and to help improve preservation. This paper reviews some techniques that have been used to aid in the development of organ preservation.

The importance of iron, calcium and free radicals in reperfusion injury: an overview of studies in ischaemic rabbit kidneys

An overview of a series of experiments attempting to link iron and calcium redistribution and release of free fatty acids with falls in pH and adenine nucleotide levels during cold storage of rabbit kidneys is presented. The data reviewed strongly suggest that these events are inextricably linked to subsequent reperfusion injury. Circumstantial evidence incriminating iron was provided by experiments showing that iron chelation decreased reperfusion injury after warm (WI) and cold ischaemia (CI) in rat skin flap and rabbit kidney models. Evidence for a role for calcium was provided when it was found that a calcium channel blocking agent added to the saline flush solution before storage inhibited lipid peroxidation, whereas chemicals which caused release or influx of calcium into the cell exacerbated oxidative damage. Additional involvement of breakdown products of adenine nucleotides was suggested by the protection from lipid peroxidation afforded by allopurinol. Involvement of calcium-activated phospholipase A2 was strongly suggested by increases in free fatty acids during cold storage and both this increase and lipid peroxidation were inhibited by addition of dibucaine to the storage solution.

Effects of chlorpromazine and methylprednisolone on perfusion preservation of rabbit livers

The isolated perfused rabbit liver was used to determine how continuous hypothermic perfusion affected liver function. Rabbit livers were perfused for 0, 24, 48, and 72 hr at 5 degrees C with the UW perfusate containing hydroxyethyl starch (5 g%) dissolved in a solution containing gluconate (80 mM), adenosine (5 mM), glutathione (3 mM), phosphate (25 mM), and additives as described previously, and they were used successfully for kidney preservation. At the end of preservation the livers were perfused in an isolated circuit with a Krebs-Henseleit solution with addition of 4 g% bovine serum albumin and 10 mM glucose at 38 degrees C for 120 min. Bile was collected from the cannulated common duct. Biliary excretions of indocyanine green and liver enzymes lactate dehydrogenase, aspartate aminotransferase, and alanine aminotransferase, were determined both in the cold perfusate and the normothermic perfusate. Livers were also studied after pretreatment of the donor with chlorpromazine (CPZ) and/or methylprednisolone (MP). Bile production (ml/120 min, 100 g liver) upon reperfusion produced the most interesting data and decreased from a control value of 10.3 +/- 2.6 to 9.3 +/- 1.0 (24 hr), 5.3 +/- 0.7 (48 hr), and 4.1 +/- 1.5 (72 hr). Enzyme release was not predictive of the degree of preservation-induced damage. Pretreatment of rabbits with a combination of CPZ/MP improved bile flow at 48 and 72 hr (8.3 +/- 3.0 and 7.0 +/- 1.3, P less than 0.05). Pretreatment with either drug alone also improved function after 72 hr of preservation (7.1 +/- 1.8, CPZ; 8.2 +/- 3.5, MP).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of drug treatment on liver-slice function following 72-hour hypothermic perfusion

The viability of hypothermically perfused dog liver was evaluated with a tissue-slice technique. After being preserved for 72 hr, slices of liver were incubated at 30 degrees C for as long as 2 hr; then water content, K+/Na+ ratio, and ATP concentration were measured. Dog livers were assigned to the following experimental groups: Group 1 (no preservation; control); Group 2 (livers preserved for 72 hr); Group 3 (donor animals pretreated with 3.5 mg/kg of chlorpromazine (CPZ) and 20 mg/kg of methylprednisolone (MP), and livers preserved for 72 hr); Group 4 (livers pretreated with 2-deoxycoformycin (2-DOC), 50 mg/liter, and preserved for 72 hr); and Group 5 (combination of Group 3 and Group 4 treatments). Livers in Groups 2, 3, and 4 lost K+ during preservation, and the mean K+/Na+ ratio significantly decreased from a control value of 4.2 +/- 0.4 to 1.5-1.9 (P less than 0.05). Group 5 livers did not lose K+; mean K+/Na+ ratio was 3.9 +/- 0.5. Fresh livers (no preservation) rapidly reaccumulated K+ when the tissue slices were incubated for 2 hr at 30 degrees C; mean K+/Na+ ratio was 3.7 +/- 0.5. Tissue slices from Group 2 livers (72 hr preservation), and livers pretreated with CPZ-MP (Group 3) or pretreated with 2-DOC (Group 4) did not significantly reaccumulate K+ at 30 degrees C; mean K+/Na+ ratio was 1.7-2.1. Only slices prepared from liver pretreated with both CPZ-MP and 2-DOC reaccumulated K+; mean K+/Na+ ratio was 4.6 +/- 1.2.(ABSTRACT TRUNCATED AT 250 WORDS)

Preservation of renal function by adenosine-stimulated ATP synthesis in hypothermically perfused dog kidneys

Dog kidneys were hypothermically perfused for 1 to 5 days in the presence or absence of adenosine (5 mM). Following 1, 3, and 5 days, kidneys were reperfused at normothermia in an isolated perfusion system using a bovine serum albumin containing perfusate and renal function was determined. At the end of normothermic perfusion, kidney cortical slices were removed for biochemical analysis. Kidneys preserved in the presence of adenosine generated much higher concentrations of ATP during normothermic perfusion than kidneys preserved in the absence of adenosine at all time periods studied. In kidneys reperfused (37 degrees C) after 3 days of preservation, the ATP concentration averaged 9.15 mumol/g dry wt (+adenosine) vs. 4.75 mumol/g dry wt (-adenosine). After 5 days, the average was 12.65 mumol/g dry wt (+adenosine) vs. 4.00 mumol/g dry wt (-adenosine). The tissue concentration of K+ was higher in kidneys perfused in the presence of adenosine for all time periods studied. The presence of adenosine had little effect on the GFR (creatinine clearance) which was reduced by about 90% from control values at both 3 and 5 days of preservation. The primary effect of adenosine on renal function was a greater preservation of the capability of the isolated perfused kidney to reabsorb Na+ from the glomerular filtrate. In the absence of adenosine Na+ reabsorption was reduced from 97 to 50% whereas in the presence of adenosine was reduced to only 80% after 3 days of preservation. After 5 days of perfusion Na+ reabsorption was unaffected by the presence of adenosine and the amount resorbed was only 25-30% of the amount filtered.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of short-term hypothermic perfusion and cold storage on function of the isolated-perfused dog kidney

The isolated-perfused dog kidney was used as a model to measure the effects of short-term hypothermic preservation on renal function and metabolism. Kidneys were cold-stored in Collins' solution, hypotonic citrate, or phosphate-buffered sucrose for 4 and 24 hr, or were continuously perfused for 4 and 24 hr with a synthetic perfusate. Following preservation kidneys were perfused with an albumin-containing perfusate at 37 degrees C for 60 min for determination of renal function. The results indicate that many of the effects of short-term preservation on renal function in dog kidneys are similar to results reported for rat and rabbit kidneys. Cold storage for 4 hr resulted in a large decrease in GFR (57%), but only a small decrease in Na reabsorption (from 97 to 87%). Cold storage for 24 hr caused a further decline in renal function (GFR = 95% decrease, Na reabsorption = 49-64%). Results were similar for all cold storage solutions tested. Perfusion for 4 hr was less damaging to renal function than cold storage. The GFR decreased only 14% and urine formation and Na reabsorption were practically normal. After 24 hr of hypothermic perfusion, the GFR was reduced by 79%, urine flow was normal, and Na reabsorption was 78%. There were no obvious biochemical correlates (adenine nucleotides, tissue edema, or electrolyte concentration) with the loss of renal function during short-term preservation. The results suggest that the isolated-perfused dog kidney can be used to test the effects of preservation on renal function, and yields results similar to those obtained using small animal models.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypothermic kidney preservation on the isolated perfused kidney: a comparison of reperfusion methods

Two isolated-perfused kidney methods were used to study the effects of hypothermic preservation on renal function in dog kidneys. The isolated-machine-perfused kidney (IMPK) used an in vitro perfusion technique--the perfusate was a Krebs-bicarbonate type delivered to the kidney at 37 degrees C by a mechanical pump at a constant pressure (100 mm Hg). The isolated-blood-perfused kidney (IBPK) utilized transplantation of the preserved kidney to the femoral vasculature. Renal function (urine analysis) was determined over a 1-hr reperfusion interval and included GFR (creatinine clearance), urine formation, and Na+ reabsorption. Kidneys preserved for only 24 hr by cold storage in either Collins'--C3 solution or in hypotonic citrate and kidneys hypothermically perfused for 24 hr demonstrated greater retention of renal function when reperfused by blood (IBPK) than with the in vitro perfusate (IMPK). The GFR was reduced by 38-58% when tested with the IBPK, but by 80-90% when tested with the IMPK. Na+ reabsorption was normal (97%) with blood reperfusion but was reduced to 36-50% in cold-stored kidneys and 82% in hypothermically perfused kidneys determined by machine reperfusion (IMPK). However, kidneys perfused for 72 hr demonstrated more similar renal functions when tested by either IMPK or IBPK. GFR was reduced to 20% (IBPK) and 11% (IMPK) and Na+ reabsorption averaged 76-85% (IBPK or IMPK). These results suggest that either reperfusion method is suitable for determining the effects of renal preservation on kidney function in kidneys preserved for 72 hr but, for short-term preserved kidneys (24 hr), the IBPK model may be preferred.