Electrolyte equilibration of human kidneys during perfusion with HTK-solution according to Bretschneider

Twelve surgically removed human kidneys (mainly tumor kidneys) were investigated. The investigations comprised perfusion criteria (perfusion flow, perfusion pressure, perfusion resistance, electrolyte equilibration). During perfusion of the kidneys with HTK solution, the perfusion resistance was nearly three times as high in human kidneys as in canine kidneys perfused under the same conditions in previous studies. Beside possible species differences the raised perfusion resistance may be explained by the greater trauma to the human kidneys due to the surgery, the primary ischemic stress which cannot be avoided clinically and the often nonoptimal initial diuresis. Nevertheless definitive perfusion is possible under clinical conditions although pronounced increases of perfusion resistance may occur. As indicated by the raised perfusion resistance of human kidneys under clinical conditions as compared with canine kidneys in an experimental model, electrolyte equilibration of human kidneys was protracted. For this reason, a duration of perfusion of at least 10 min is necessary in clinical application of HTK solution, i.e., longer than in animal experiments.     

Pulmonary effects of autotransfused blood. A comparison of fresh autologous and stored blood with blood retrieved from the pleural cavity in an in situ lung perfusion model

An in situ pulmonary lobe perfusion model in dogs was used to examine the pulmonary effects of autotransfused blood as compared with fresh and stored blood. Fresh arterial blood was collected in heparin solution from ten dogs and was drained into and collected from the pleural cavity using a commercially available autotransfusion device for continuous filtration. Results of perfusion with autotransfused blood were compared with results of perfusion of blood stored at 4 °C in ACD solution for twenty-four hours in seven dogs and those of perfusion of blood stored for twenty-one days at 4 °C in ACD solution in seven dogs. The fresh and stored blood samples were passed through a standard recipient set filter prior to perfusion.Perfusion with autotransfused blood resulted in a decreased arteriovenous pO₂ gradient as compared with results in control blood, but there was no concomitant elevation in pulmonary vascular resistance (PVR) or endobronchial pressure (P_b) for the autotransfused blood. Stored blood by comparison showed significantly increased PVR and P_b but a progressive decline in A-VpO₂ which was in excess of the level reached by perfusion of autotransfused blood. Fresh blood showed essentially no change in pulmonary functional parameters during perfusion.The great majority of animals whose lungs were perfused with stored blood had microscopic evidence of interstitial pulmonary edema, perivascular hemorrhage, intra-alveolar fluid, and alveolar congestion. Significantly fewer animals showed these changes when lungs were perfused with autotransfused or fresh blood. Wet-dry weight ratios of lung tissue after perfusion indicated significantly higher uptake of water by the lung perfused with stored blood than by those perfused with autotransfused or fresh blood.     

255. Energiestoffwechsel und Elektrolytveränderungen im Myokard der Ratte nach hypotfiermer Konservierung und in der Erholung

Zusammenfassung Das Ausmaß metabolischer Veränderungen nach einer 4stündigen Konservierung bei 2° C und ihre Reversibilität während anschließender parabiotischer Perfusion bei 37° C wurden in 180 Rattenherzen durch Bestimmung der energiereichen Phosphate und der Gewebswasser- und Elektrolytgehalte untersucht: 1. Kontinuierliche aerobe Perfusion mit oxygenierter Ringer-Lösung erhält nahezu normale Werte des Energiestoffwechsels am Ende der Konservierung, führt aber zu einer Schwellung mit einem Anstieg des Gewebsnatriums auf 300°/u und einem Abfall des Kaliums auf 70°/u. Während anschließender Hämoperfusion bewirkt dieses Ödem eine eingeschränkte Organdurchblutung und Gewebshypoxie. 2. Perfusion mit Nz äquilibrierter Ringer-Lösung vermindert gegenüber der aeroben Perfusion die Reserven an energiereichem Substrat, produziert aber kein stärkeres Ödem. Addition von Hypoxie und Schwellung bedingt die schlechteste Erholung in dieser Gruppe. 3. Nach einfacher hypothermer Lagerung bei 2° C findet sich das größte energetische Defizit, jedoch die geringste Wasseraufnahme und die beste Erholung der Substrat- und Elektrolytveränderungen. 4. Zwischen Kaliumverlust und Wasseraufnahme in allen Gruppen besteht eine lineare Beziehung, die mit zunehmender Schädigung und während Erholung in beiden Richtungen durchlaufen wird.

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Energy metabolism and electrolyte changes in the myocardium of rats after hypothermic preservation and during recovery

Summary The extent of metabolic changes after 4 h preservation at 2° C and their reversability during subsequent parabiotic perfusion at 37° C were examined in 180 rat hearts by determining high-energy phosphates and the tissue fluid and electrolyte contents. 1. Continuous aerobic perfusion with oxygenated Ringer's solution produces nearly normal energy metabolism values at the end of preservation but leads to swelling with a rise of tissue sodium to 300% and a fall of potassium to 70%. During subsequent hemoperfusion this edema causes a restriction of organ perfusion with tissue hypoxia. 2. Perfusion with N₂-equilibrated Ringer's solution, compared with aerobic perfusion, reduces the reserves of energy-rich substrates but does not produce more edema. The combination of hypoxia and swelling produces the poorest recovery in this group. 3. After simple hypothermic storage at 2° C we find the greatest energy deficit but the lowest water retention and the best recovery of substrate and electrolyte changes. 4. Between potassium loss and water retention there is in all groups a linear relation which is maintained both with increasing damage and during revocery.

     

Short time in-situ preservation of the ischemic kidney by a simple initial hypothermic perfusion with various cold solutions. An animal experimental study]

In unilateral nephrectomized beagle dogs the remaining kidney was subjected to 2 hrs of ischemia in situ. The ischemic organ was cooled to 22--23 degrees C by initial hypothermic perfusion over a 5-F catheter introduced into the renal artery via the carotid artery. It was then left in the open abdominal wound without any further attempts of cooling. Three perfusates were used: an isoosmolar Dextran solution (Eisenberger), a hyperosmolar, "intracellular" electrolyte solution (Sacks), and a hyperosmolar, "extracellular" electrolyte solution. There was a mean postoperative increase in serum creatinine levels of 0.6 mg-%. By the 3rd p.o. day at latest the serum creatinine was again within normal limits. The inulin and PAH clearances on the 7th and 14th p.o. day showed no significant differences to preoperative determinations. No definite advantage or disadvantage was noted among the three perfusates. All control dogs whose kidneys were made ischemic for 2 hrs without perfusion died due to acute tubular necrosis. Apparently the homogenous cooling and flushing by the initial perfusion is of more importance for good preservation in this situation than the composition of the perfusate.     

Calcium ion concentration of machine perfusate predicts early graft function in expanded criteria donor kidneys

Pulsatile preservation offers the advantage of pretransplant assessment of donor kidneys. Selected electrolyte concentrations of machine perfusate were measured over time in order to: (1) describe electrolyte changes in perfusate during the pulsatile preservation of expanded-criteria donor (ECD) kidneys, and (2) to assess the prognostic significance of these characteristics to early graft function. One hundred and fifty ECD kidneys were preserved in our laboratory between 1 January 1995 and 11 January 1997. ECD kidneys were defined as those requiring pretransplant biopsy. Kidneys were grouped by the presence or absence of delayed graft function (DGF), and perfusion parameters were measured every hour during pulsatile perfusion. All kidneys were preserved by continuous hypothermic pulsatile perfusion using Belzer II solution. Renal flow is decreased and renal resistance is increased in the presence of DGF in machine-preserved ECD kidneys. In addition, ionized calcium concentration of the machine perfusate is significantly elevated in the DGF group compared with the No DGF group (0.091 vs 0.054, P = 0.0016). The incidence of DGF is significantly lower in the ECD kidney. Among the pretransplant variables of donor characteristics, perfusion parameters and histology, perfusion parameters are highly predictive of early graft function. In addition, we found that ionized calcium concentration in the perfusate is significantly elevated in kidneys exhibiting DGF, which may have implications for assessing the suitability of donor kidneys for transplantation. Received: 10 August 1998 Received after revision: 9 March 1999 Accepted: 25 June 1999     

The effects of balanced versus saline-based hetastarch and crystalloid solutions on acid-base and electrolyte status and gastric mucosal perfusion in elderly surgical patients

The IV administration of sodium chloride solutions may produce a metabolic acidosis and gastrointestinal dysfunction. We designed this trial to determine whether, in elderly surgical patients, crystalloid and colloid solutions with a more physiologically balanced electrolyte formulation, such as Hartmann's solution and Hextend, can provide a superior metabolic environment and improved indices of organ perfusion when compared with saline-based fluids. Forty-seven elderly patients undergoing major surgery were randomly allocated to one of two study groups. Patients in the Balanced Fluid group received an intraoperative fluid regimen that consisted of Hartmann's solution and 6% hetastarch in balanced electrolyte and glucose injection (Hextend). Patients in the Saline group were given 0.9% sodium chloride solution and 6% hetastarch in 0.9% sodium chloride solution (Hespan). Biochemical indices and acid-base balance were determined. Gastric tonometry was used as a reflection of splanchnic perfusion. Postoperative chloride levels demonstrated a larger increase in the Saline group than the Balanced Fluid group (9.8 vs 3.3 mmol/L, P = 0.0001). Postoperative standard base excess showed a larger decline in the Saline group than the Balanced Fluid group (-5.5 vs -0.9 mmol/L, P = 0.0001). Two-thirds of patients in the Saline group, but none in the Balanced Fluid group, developed postoperative hyperchloremic metabolic acidosis (P = 0.0001). Gastric tonometry indicated a larger increase in the CO2 gap during surgery in the Saline group compared with the Balanced Fluid group (1.7 vs 0.9 kPa, P = 0.0394). In this study, the use of balanced crystalloid and colloid solutions in elderly surgical patients prevented the development of hyperchloremic metabolic acidosis and resulted in improved gastric mucosal perfusion when compared with saline-based solutions. IMPLICATIONS: This prospective, randomized, blinded trial showed that, in elderly surgical patients, the use of balanced IV solutions can prevent the development of hyperchloremic metabolic acidosis and provide better gastric mucosal perfusion compared with saline-based fluids.     

A SIMPLIFIED KIDNEY PRESERVATION SYSTEM: THE USE OF HYPEROSMOLAR PERFUSATES FOR CONTINUOUS PERFUSION PRESERVATION OF CANINE KIDNEYS

Since the quality of renal preservation following simple ice storage is improved by the use of hyperosmolar washout solutions, hyperosmolar perfusates were evaluated for continuous perfusion preservation. Canine kidneys were preserved for 48 hours by continuous perfusion at 5°C, using hyperosmolar cryoprecipitated plasma and 5% albumin perfusates of osmolalities 397 to 430 mOsm/kg H₂O. Hyperosmolar plasma gave significantly better preservation than isosmolar plasma, but the results were only marginally sperior to those already obtainable with isosmolar albumin solution. No further improvement in preservation by albumin perfusion was obtained with the hyperosmolar formulations. Because isosmolar albumin solution is easier to prepare than hyperosmolar cryoprecipitated plasma and gives comparable results, it remains our perfusate of choice for continuous perfusion preservation.     

Kidney transplantation from non-heart-beating donors after oxygenated low-flow machine perfusion preservation with histidine–tryptophan–ketoglutarate solution

The aim of this study was to determine the potential benefit of aerobic machine preservation (MP) with non-colloidal histidine–tryptophan–ketoglutarate (HTK) solution compared with MP with Belzer machine perfusion solution (MPS) and standard cold storage, after marginal kidneys had been obtained from non-heart-beating donors. Cardiac arrest was electrically induced in anaesthetized German landrace pigs (20–25 kg bw). Their kidneys were harvested 40 min thereafter, flushed with HTK by gravity of 100 cm H₂O via the renal artery and then stored in HTK for 18 h at 4°C. Other organs were subjected to oxygenated (pO₂>500 mmHg) hypothermic pulsatile low-flow machine perfusion with HTK or MP with Belzer MPS at P_max=40 mmHg, yielding transrenal flow values of 0.2–0.3 ml/min per g with HTK and approximately twice that amount with Belzer MPS. A well-preserved vascular endothelium and intact tubular epithelium were documented by electron microscopy at the end of perfusion preservation in both solutions as well as after cold storage. Concentrations of ATP (in micromoles per gramme) in tissue homogenates at the end of perfusion preservation with HTK were 1.18±0.12 vs 0.16±0.02 (P<0.05) after simple cold storage and 2.43±0.23 after perfusion with Belzer MPS, thus documenting a relevant effect of low-flow perfusion on tissue oxygenation. Viability of the grafts was followed for 1 week after heterotopic transplantation and bilateral nephrectomy in the recipient pigs. Machine perfusion with HTK significantly improved cortical microcirculation upon early reperfusion in vivo, as well as maximal serum levels of urea and creatinine, compared to recipients receiving cold-stored grafts. No differences could be found between MP with HTK or Belzer MPS. In conclusion, provision of oxygen during storage is possible by low-flow perfusion with HTK as with Belzer MPS and apparently improves graft viability after transplantation.     

Histological features of stored kidneys after simple hypothermic perfusion with preserving solutions of different types

Four different preserving fluids were studied for protective effect in a total of 33 isolated canine kidneys. The preservation method consisted in initial perfusion followed by 24 hours of hypothermic storage. Two electrolyte and two non-electrolyte solutions were tested. One of the electrolyte solutions was of the extracellular, the other of the intracellular type. The two non-electrolyte solutions were 5% human albumin and 10% Rheomacrodex. On the evidence of serial microscopic studies the Collins-4 solution of intracellular type allows the best viability: even the 24-hour specimens exhibited a normal renal structure. Of the non-electrolyte solutions Rheomacrodex revealed an adequate protective effect despite the production of a marked interstitial oedema and signs of dehydration involving the tubular cells. The 5% human albumin solution failed to preserve the integrity of renal structure for 24 hours. The electrolyte solution of extracellular type proved still less satisfactory, the glomerular loops and the tubular epithelium reveling signs of autolysis by the end of the 24-hour period.     

Techniques for perfusion and storage of heterotopic heart transplants in mice

Organ pretreatment prior to transplantation has assumed increasing importance. We studied the ability to preserve and perfuse hearts in well-defined genetic mouse models, prior to heterotopic engraftment. Hearts were manually perfused through the aortic root and stored in a variety of cold solutions or were perfused using a continuous perfusion pump. Different electrolyte solutions, mouse strains, perfusion, and storage times as well as perfusion volumes were studied. Treated hearts were than transplanted heterotopically and short- and long-term function assessed. Hearts stored for more than 1 hour in cold solutions (saline 0.9%, or lactated Ringer's) failed to function. Hearts perfused with 0.25-0.4 ml of cold solution for a maximum of 30 minutes functioned well after transplantation. C3H (H-2k) mice provided the most resilient hearts. We conclude that short-term perfusion or storage of mouse hearts is feasible and should provide an excellent model for the study of organ pretreatment with monoclonal antibodies or other agents prior to transplantation.     

Plasma Colloid Osmotic Pressure During Open-Heart Surgery Using Non-Colloid or Colloid Priming Solution in the Extracorporeal Circuit

Two different priming solutions for the heart-lung machine were compared in 14 patients during aortic valve replacement. Colloid osmotic pressure (COP), and albumin in plasma, blood erythrocyte volume fraction (B-EVF) and arterial oxygen tension (PaO₂) (FIO₂ = 1.0) were followed before, during and after perfusion. The two priming solutions were 2000 ml Ringerdex^® (7 patients) or 1800 ml Ringerdex + 200 ml 20% albumin^® (7 patients). COP and B-EVF were normal before bypass. After 10 min on bypass, when about 1 000 ml of crystalloid cardioplegic solution had been given, COP was reduced by about 50% and B-EVF fell to 23%, indicating a small loss of water from the circulation when compared with in vitro dilution curves. COP was slightly lower in the non-colloid group (p < 0.02). Both COP and B-EVF remained unchanged during perfusion, despite transfusica from the heart-lung machine of a mixture of blood and crystalloid solution with a calculated very low COP (6 mmHg) and B-EVF (15 %). After perfusion the restitution of COP and B-EVF was rapid and parallel. Both returned to normal levels after 2 hours. There was a good correlation between COP and albumin measured in the same plasma samples (r = 0.83, p < 0.001). At one hour after bypass PaO₂ (FIO₂ = 1.0) tended to decrease in the non-colloid group, compared with the preperfusion level. 40 g of albumin was a too small amount of colloid to diminish substantially the reduction of COP during perfusion. The unchanged levels of COP and B-EVF during perfusion, despite further dilution as well as the parallel normalization after perfusion, can only be explained by loss of water from the circulation.     

Comparison of Functional and Metabolic Assessments in Preservation Techniques for Heart Transplantation

The present study compares simple hypothermic storage and hypothermic perfusion in a swine model of heart transplantation using metabolic and functional assessments. In both groups the hearts were initially protected with iso-osmolar potassium Tyers cardioplegia. The donor hearts of group A were placed in simple hypothermic storage for 5 h. The donor hearts of group B were placed onto a perfusion apparatus for 5 h with perfusion pressure maintained at 28 cm of H₂O and a myocardial temperature of 8–10 °C. The perfustate consisted of Tyers' solution with the addition of 2 mg/L of mannitol, 12.5 mg/L of glucose, 5 units/L of insulin, and 95% oxygen. The ischemic interval within both groups was 6 h, including orthotoipic transplantation. Investigation was conducted at three time periods: prepreservation (T₁) in the donor, and postpreservation (T₂) and immediately after loading (T₃) in the recipient. Following volume loading for the hypothermic perfusion group there was significant improvement of myocardial function (cardiac index, p <. 05; stroke index, p <. 05) with no significant change in systemic vascular resistance, systemic blood pressure, and heart rate. There was also significant improvement in myocardial performance (p <. 05) for the hypothermic perfusion group following volume loading. Results of fatty acid turnover using 15-p-iodo (¹²³I)-phenylpentodecanoic acid indicate significantly greater increase in metabolic rale for the perfusion group than for the hypothermic storage group, (p <. 05) This indicates improved metabolic status of the heart treated with the hypothermic perfusion technique. We conclude that a combination of functional and metabolic assessments is a good method for deduction of ischemic-reperfusion injury. He also conclude that hypothermic perfusion is superior to hypothermic storage for in vitro preservation of hearts for heart transplantation.     

Effects of different perfusates on functional parameters of isolated perfused dog kidneys.

BACKGROUND: The isolated perfused canine kidney has been established as a valid model for conducting both renal physiology and transplantation research. This model is of particular importance for developing new strategies to improve graft function after renal transplantation. In the present study, a newly developed method using isolated haemoperfused porcine kidneys was adapted for use in canine kidneys. In contrast to haemoperfusion, synthetic perfusion media can be standardized and can prevent the initiation of blood-mediated reperfusion reactions. Thus, an additional aim was to determine whether blood could be replaced by synthetic cell-free perfusion solutions. METHODS: Canine kidneys (n = 30) were harvested from donors euthanized in veterinary practices for causes unrelated to the present study. The kidneys were isolated and perfused with autologous blood or cell-free synthetic electrolyte buffer (Tyrode solution). During perfusion, we monitored renal perfusate flow (RPF), glomerular filtration rate (GFR), electrolyte and glucose reabsorption, oxygen consumption and urine concentration. RESULTS: Changes in perfusion medium did not affect the RPF. In contrast, GFR, urine concentration and oxygen consumption were significantly higher, whereas fractional excretion of sodium and glucose were significantly lower in blood- than in Tyrode-perfused kidneys. CONCLUSIONS: This system offers a simple model for studying whole-organ functional alterations after acute renal ischaemia. Renal function indicators were below values reported during in vivo physiological conditions. These functions were better conserved when kidneys were perfused with autologous blood than with Tyrode.     

Fluosol-Da: An Artificial Blood for Total Cardiopulmonary Bypass

The isolated, in situ pig heart model was used to determine if Fluosol could support myocardial function during cardiopulmonary bypass. Fourteen pigs were utilized; 7 underwent studies of myocardial metabolism (coronary blood flow and vascular resistance, myocardial oxygen consumption and extraction, lactate extraction, and adenosine triphosphate and creatine phosphate levels), and 7 underwent studies of myocardial contractility and compliance (intraventricular balloon measurements). Each study was carried out utilizing one hour of control hemic perfusion, followed by one hour of Fluosol perfusion, and followed by a third hour of a return of hemic perfusion.The results documented that in the vented, beating, nonischemic heart, myocardial metabolism and functional measurements are maintained during an hour of Fluosol perfusion. However, because of an increased level of ionized calcium during Fluosol perfusion, myocardial functional measurements document significantly increased contractility. The increased contractility is associated with an increase in anaerobic metabolism. The latter contributes to a decline in the high-energy phosphate level following a return of hemic perfusion as the heart recovers from the increased work load placed on it during Fluosol perfusion.It is concluded that there is sufficient oxygen-carrying capacity in Fluosol-DA to maintain cardiac function during perfusion in the large animal model. However, the carrier solution for the Fluosol must be adjusted to appropriate electrolyte content to avoid adverse effects on the myocardium.     

Ex vivo renal surgery. Further use of a new perfusate

Ex vivo renal operations were performed in fifteen dogs to determine the efficacy of a new ex vivo renal preservation technic. The method described and illustrated in this report proved to be simple and requires neither continuous renal cooling nor continuous renal perfusion. A single initial perfusion of the totally ischemic canine kidney with a new hyperosmolar intracellular electrolyte solution was able to offer cellular protection from the otherwise lethal effect of ambiothermic exposure for up to five hours without significant loss of renal function. Pre- and postoperative serum creatinine levels were assessed to determine renal function. Ex vivo renal surgical technics have important potential application when in situ repair is too hazardous or its effect uncertain.     

The effect of two different renal preservation methods on canine renal allograft survival

Summary Preservation of human cadaver kidneys for transplantation has been achieved primarily by two methods, hypothermic pulsatile perfusion with cryoprecipitated plasma and cold storage with an electrolyte solution. It has been suggested that pulsatile perfusion results in an increased antigenicity of the transplanted kidney. To investigate the possibility that pulsatile perfusion causes changes which may accelerate allograft rejection, machine preservation was compared with simple cold storage. The kidneys were preserved by either one of the two methods for 6 or 24 hours followed by allotransplantation in nephrectomised dogs. No immunosuppressive drugs were given.Kidneys which were allografted without undergoing any preservation (0 hrs) had a mean survival time of 10.4±1.7 days (n=5). Kidneys preserved by machine perfusion for 6 and 24 hours survived for 9.6±1.4 (n=5) and 10.9±1.3 (n=9) days respectively. The mean suryival time for simple cold storage for 6 and 24 hours was 9.3±1.3 (n=7) and 12.0±1.9 (n=6) days. Our findings suggest that in kidneys exposed to minimal warm ischaemia there is no significant difference between the two methods of preservation on renal allograft survival for the time intervals tested.     

Hypothermic perfusion of rabbit kidneys with solutions containing gelatin polypeptides.

Rabbit kidneys were perfused with a solution of extracellular electrolyte composition, made hypertonic with glucose and containing the gelatin polypeptide preparation Haemaccel (Hoechst) as the only colloid. Perfusions were carried out at 5 and 10 C for 19 hr, and function was tested by autografting. All of the kidneys perfused at the higher temperature showed immediate life-sustaining function after transplantation and contralateral nephrectomy, whereas only one graft of five perfused at the lower temperature showed any function. The suitability of the Haemaccel solution as a vehicle for introducing the cryoprotective agent glycerol was tested by perfusing kidneys for 4 hr with a solutiont containing 2% glycerol; the function of these organs was similar to that of kidneys transplanted without perfusion. Ultrastructural examination of kidneys perfused for 24 hr at 10 C showed excellent structural preservation, but measurements of water and ion contents and the penetration of marker molecules in nonmetabolizing kidneys showed 2.8% Haemaccel to be somewhat less effective than 6% bovine serum albumin in stabilizing these values. The Haemaccel perfusate is considered to be highly suitable for the introduction and removal of cryoprotective agents, and the results of hypothermic preservation by continuous perfusion are encouraging.     

Functional preservation of the mammalian kidney. V. pharmacokinetics of dimethyl sulfoxide (1.4M) in kidneys (rabbit and dog) perfused at 37, 25, or 10 degrees C followed by transplantation (dog).

Rabbit and dog kidneys were perfused for 30 min at 37°C with 1.4 M [³H]Me₂SO in a K⁺-Mg²⁺?rich perfusate. Subsequently the kidneys were perfused for 30 min with Me₂SO-free perfusate. The rate of Me₂SO uptake and washout as well as Me₂SO distribution in the tissue were determined. It was found that equilibrium conditions were achieved within 30 min for both uptake and washout with $\text{T}\text{M}$ ratios approaching 1.0. The amount of Me₂SO in the cortex and medulla of rabbit kidneys was not significantly different. The same experiment was repeated with dog kidneys at 25 and 10°C. At these lower temperatures the rate of uptake and washout was significantly less, but the final concentration achieved within 30 min was the same as at 37°C. Dog kidneys flushed with a K⁺?Mg²⁺?rich solution, with or without 1.4 M dimethyl sulfoxide (Me₂SO), were kept at 10°C, then reimplanted in the autologous host, and an immediate contralateral nephrectomy was performed. Of the dogs receiving kidneys treated with Me₂SO-free solution, 86% survived; of the dogs receiving Me₂SO-treated kidneys, 75% survived. Dog kidneys were perfused for 30 min with a K⁺?Mg²⁺?rich solution, with or without 1.4 M Me₂SO, at 25 or 37°C. All kidneys were then perfused for 30 min with a Me₂SO-free solution at the same temperature used for the first perfusion. All kidneys were then reimplanted in the autologous host and an immediate contralateral nephrectomy was performed. Of the dogs receiving kidneys perfused at 25°C with Me₂SO-free solution, 43% survived; of the dogs receiving kidneys perfused with Me₂SO, 42% survived. Dog kidneys were also treated at 37°C in a manner similar to those at 25°C. Of the dogs receiving kidneys perfused at 37°C with Me₂SO-free solution, 80% survived; of the dogs receiving kidneys perfused with Me₂SO, 67% survived. Other results indicate that perfusion with a closed circuit is superior to perfusion with an open circuit. Also, gradual administration and washout of Me₂SO gives better renal survival than rapid changes in Me₂SO concentration.     

Improved microcirculation by low‐viscosity histidine– tryptophan–ketoglutarate graft flush and subsequent cold storage in University of Wisconsin solution: results of an orthotopic rat liver transplantation model

As previously shown in a model of isolated rat liver perfusion, the combined use of an initial graft flush with low‐viscosity histidine–tryptophan–ketoglutarate (HTK) solution followed by cold storage in University of Wisconsin (UW) solution markedly improved the preservation during an extended cold storage period. In this study, we aimed to transfer our results into an in vivo model of orthotopic rat liver transplantation, and to elucidate the potential mechanism of the improved preservation by focusing on the hepatic microcirculation. Livers were harvested from male Wistar rats. Aortic perfusion with a pressure of 100 cm H₂O was performed with either UW (group UW) or HTK (groups UW and HTK_UW), followed by additional back‐table perfusion with UW (group HTK_UW). After 20‐h cold storage at 4 °C, livers were orthotopically transplanted with reconstructing the hepatic artery. As measured by bile flow and liver enzymes, HTK flush followed by UW storage was superior compared to single use of either UW or HTK solution. The hepatic microcirculation was significantly improved, as shown by the increased percentage of reperfused sinusoids and reduced sinusoidal leucostasis. HTK and UW effectively reduce ischaemia‐reperfusion injury after liver transplantation. By combining the comparative advantages of both solutions, a cumulative effect resulting in an improved preservation was shown. Thus, this mechanism improves microcirculatory reperfusion.     

Energy demand of cardioplegically perfused human hearts

Human adult hearts with aortic valve disease (n = 20) and hypertrophic obstructive cardiomyopathy (n = 1) were perfused intraoperatively with cold histidine buffered Bretschneider solution. During a seven minute cardioplegic perfusion the temperature level, the electrolyte level, the resistance of the left (LCA) and right coronary artery (RCA), and myocardial O2 consumption were analysed. Equilibration of K+ was terminated shortly after the start of the perfusion while Na+ equilibration lasted for about 5 minutes. Resistance of RCA did not change significantly, but that of the LCA was diminished significantly (p less than 0.025) within the perfusion period indicating a delayed washout of calcium from the extracellular space. Myocardial O2 consumption was reduced from 2.71 ml/min (1. minute) to 1.51 ml/min (4. minute) to 0.93 ml/min (7. minute) although the temperature had reached a low level after 3 minutes. The difference between 4. to 7. minutes is significant (p less than 0.001). By our results it is concluded that in adult hearts high-volume cardioplegic perfusion at a flow rate of 1 ml/min X gm at a perfusion pressure of 40 to 50 mmHg should be performed for at least 6 to 7 minutes to achieve a sufficient intra-ischemic myocardial protection.