Evidence of free-radical-induced damage in rabbit kidneys after simple hypothermic preservation and autotransplantation.

Rabbit kidneys were stored for 24 or 48 hr at 0 degree C after single-passage vascular flush with 30 ml of cold hypertonic citrate solution or 0.9% isotonic sodium chloride solution. They were then subjected to in vitro biochemical assay for evidence of free-radical damage immediately after storage or after they had been orthotopically autotransplanted and reperfused with blood in vivo for 60 min. Kidney homogenates were incubated at 37 degrees C and assayed for fluorescent conjugated Schiff bases as indicators of lipid peroxidation, as well as for superoxide dismutase activity and reduced and oxidized glutathione. In kidneys flushed with hypertonic citrate, no evidence of peroxidation could be detected immediately after storage for 24 or 48 hr. However, after in vivo reperfusion significantly more peroxidation (P less than 0.01) was evident. Storage in isotonic saline solution produced still higher levels of peroxidation damage whether reperfused or not (P less than 0.001). Schiff base formation was inversely proportional to the reduced and oxidized glutathione levels measured. No changes in superoxide dismutase levels could be detected. It is concluded that lipid peroxidation is important during cold ischemia but most damage occurs during the 60-min of reperfusion in vivo immediately after transplantation.

Function of single rat lung isografts after 48-hour cold storage. The effect of treatment with free radical antagonists and prostacyclin PGI2.

Single orthotopic rat lung isografts were carried out in adult male AS rats after 48-hour cold storage (0 degrees C). Grafts were preserved by simple organ flush followed by low-temperature immersion. Hypertonic citrate (HCA) without additives was evaluated as the basic flush solution. In other groups desferrioxamine (an iron chelator), verapamil (a calcium channel blocker) and prostacyclin (PGI2) were added separately to HCA and given intravenously to donor and recipient animals in an attempt to improve the preservation. Baseline controls were fresh HCA-flushed lungs grafted immediately after harvest. Negative controls to the HCA assessment were lungs flushed with isotonic saline (NaCl) stored for 48 hr at 0 degrees C. Functional studies were carried out at weekly intervals until sacrifice (in the fifth postoperative week) and included assessment of blood flow, aeration and gas transfer by perfusion scintigraphy, chest roentgenograms, and blood gas analysis. Of the baseline control animals, 10/10 survived to the end of the study period; all grafts appeared macroscopically normal and blood gas analysis showed good function. Of the animals grafted with HCA-flushed, 48-hr-stored lungs 2/10 died postoperatively; 7/10 grafts appeared macroscopically normal at the end of the study, and one was slightly reduced in size. Blood gas analysis of HCA-flushed, 48-hr-stored lungs showed function similar to that of baseline control grafts. NaCl-flushed lungs (negative controls) survived surprisingly well: 3/10 animals died postoperatively, 6/10 lungs appeared normal, and one was reduced in size. Assessment of graft function showed no significant benefit of HCA flush compared with NaCl. Treatment with desferrioxamine, verapamil or prostacyclin (PGI2) failed to improve the outcome after HCA flush; in fact desferrioxamine gave significantly poorer results. The study has shown that successful 48-hr preservation of rat lung isografts can be achieved by simple organ flush with HCA and storage at 0 degrees C. Contrary to expectation and experience with preservation of other organs, rat lungs were remarkably well preserved after flush with NaCl.

Metomidate, etomidate and fentanyl as injectable anaesthetic agents in mice.

Light surgical anaesthesia lasting 12-15 min was produced by metomidate at 50 mg/kg and by etomidate at 30 mg/kg after intraperitoneal injection. Full surgical anaesthesia lasting about 160 min was achieved after subcutaneous injection of a metomidate-fentanyl mixture (60 mg/kg: 0.06 mg/kg) and this proved superior to etomidate-fentanyl given subcutaneously or intraperitoneally. It was concluded that metomidate-fentanyl is superior to pentobarbitone and tribromoethanol as an injectable anaesthetic for mice.

Neuroleptanalgesia in the rabbit.

The efficacy of the neuroleptanalgesic combinations of fentanyl-fluanisone with diazepam; and etorphine-methotrimeprazine, either alone, or with diazepam, was investigated in the rabbit. The effects of these drugs on some cardiovascular variables were studied in chronically catheterized rabbits. Fentanyl-fluanisone and diazepam produced good surgical anaesthesia. Although respiratory depression occurred, this had little effect on blood gas values. In contrast, etorphine-methotrimeprazine and diazepam produced severe respiratory depression with consequent hypercapnia and acidosis.

Ketamine alone and combined with diazepam or xylazine in laboratory animals: a 10 year experience.

Ketamine alone or supplemented by diazepam or xylazine has been used and evaluated as an anaesthetic in a range of animals including snakes, tortoises, lizards, birds, ferrets, dogs, cats, pigs, sheep, goats, non-human primates, rabbits, guinea pigs, rats, mice and hamsters. Ketamine alone has severe limitations in most species, but in combination has proved valuable.

Pregnancy after autografting and allografting vascularized ovaries and en bloc vascularized ovaries with adnexa in rabbits.

Initially, techniques for autografting ovaries with or without adnexa were developed but a 30% vascular failure rate was experienced by day 14. Of the technically successful grafts, 50% proved fertile. Single vascularized ovaries with their oviducts were then allografted into bilaterally ovariectomized rabbits by microsurgical techniques and the vascular failure rate was reduced to 5% of 40 grafts. The time-course of rejection in untreated recipients was mapped by histological examination and by 24-h culture of fallopian tubes after autopsy at different times after transplantation. Control allografts were consistently rejected by day 20. Striking prolongation of both types of graft was obtained with a short 17-day course of cyclosporin A at 10 or 15 mg day-1 kg-1. Indeed, significant evidence of rejection was found in only two ovaries out of 20 so far examined histologically. Mating behaviour, ovulation, ciliary function and transport of ova appeared normal in 80% of the recipients as long as 18 weeks after stopping cyclosporin A treatment. Only one of the ovarian allografted rabbits has so far been mated and this produced seven normal young 126 days after transplantation. However, none of the five animals mated after being allografted with en bloc adnexa have so far become pregnant.

Vascularized whole knee joint allografts in rabbits immunosuppressed with cyclosporin A.

To develop the surgical model, whole knee joints including the distal femur, proximal tibia, and joint capsule, were raised on a vascular pedicle and then replanted at the same site. Rigid fixation of the bones was achieved using two mini-plates on the tibia and femur. Revascularization of the knee was accomplished by end-to-end anastomosis of the popliteal vessels using standard microvascular techniques, and the vascular and neural supplies to the lower leg and foot were preserved. A total of 21 vascularized whole knee allografts were then similarly performed on a microvascular pedicle between two incompatible strains of rabbit. In a control group of six adult animals, no immunosuppression was administered. Two of these joints were harvested at 1 week and had patent popliteal arteries. The remaining four joints were harvested at 2-3 weeks when they were deteriorating and were found to have occluded popliteal vessels by arteriography. Eight adult allograft recipients were immunosuppressed with cyclosporin A (CyA) at 15 mg/kg per day. One allograft failed at 10 days due to femoral fracture. None of the remaining seven were rejected acutely, and three of them had patent vessels by arteriography and live bone and cartilage by light microscopy when harvested 100 days after transplantation. In another group, seven knee joints were allografted into immature rabbits immunosuppressed with CyA. Again, none rejected acutely, and 90 days later two of the seven allografts had patent vessels by arteriography, growth by serial radiographs, and live bone and cartilage by histological examination. This pilot study suggests that CyA will be useful as an immunosuppressive agent in the study of vascularized bone and cartilage transplantation, and that experimental epiphyseal plate allografting is possible in rabbits.

Protection against oxidative damage in cold-stored rabbit kidneys by desferrioxamine and indomethacin.

The storage of rabbit kidneys in hypertonic citrate solution at 0 degree C for 48-72 hr of cold ischemia resulted in oxidative damage to membranes as measured by the in vitro formation of two markers of lipid peroxidation (Schiff's base and thiobarbituric acid (TBA)-reactive material). This damage was further increased when the organs were autografted and reperfused for 60 min. The intravenous (iv) administration of desferrioxamine (a powerful iron-chelating agent) prior to the removal of the kidneys reduced the production of Schiff's bases and TBA-reactive material to low levels in the cortex of stored kidneys and decreased these measures of lipid peroxidation in the medulla by approximately 50%. Intravenous administration of indomethacin (a cyclooxygenase inhibitor) had no effect on the rate of lipid peroxidation in the renal cortex, but significantly reduced the formation of TBA-reactive material and Schiff's bases in the medulla of kidneys following storage for 72 hr. The existence of two separate pathways of lipid peroxidation (one iron-catalyzed and the other cyclooxygenase-catalyzed) in the medulla of stored kidneys was further confirmed when administration of desferrioxamine and indomethacin together resulted in significantly greater protection against lipid peroxidation than when these compounds were administered singly. The value of this combination of agents for protecting kidneys against the damage due to cold ischemia followed by reperfusion was further suggested by a trend toward improved long-term survival of the animals following replantation of the stored kidneys.

Allopurinol inhibits lipid peroxidation in warm ischaemic and reperfused rabbit kidneys.

Rabbit kidneys were subjected to 120 min of warm ischaemia or to 120 min of warm ischaemia followed by 60 min reperfusion with blood in vivo before being removed, homogenised and incubated at 37 degrees C for 90 min. Lipid extracts were obtained and monitored for Schiff base (fluorescence emission 400-450 nm, excited at 360 nm), thiobarbituric acid (TBA)-reactive material (emission 553 nm, excited at 515 nm) and diene conjugates (absorbance at 237 nm). Samples removed before incubation were assayed for reduced glutathione (GSH) and oxidised glutathione (GSSG) to provide an index of glutathione redox activity (GSH:GSSG). Allopurinol injected systemically i.v. (a) 15 mins before kidneys were clamped, (b) 15 mins before they were reperfused or (c) as two injections (before clamping and before reperfusion) significantly inhibited these biochemical markers of lipid peroxidation. Administration before reperfusion had a markedly more pronounced effect than when allopurinol was given before warm ischaemia only. It is concluded that allopurinol is probably effective because of its ability to inhibit xanthine oxidase and consequently lipid peroxidation during reperfusion rather than by preventing loss of purine nucleotides from hypoxic cells during ischaemia.

Plasma and mucosal histamine after small bowel transplantation in rats.

During the course of a study on preservation of small bowel transplants in rats, the hypothesis that histamine may play a role in graft damage has been investigated. Plasma and mucosal histamine levels have been measured after storage and reperfusion of Lewis rat small bowel transplants which have received an intravascular flush of saline or of one of the tissue preservation media, hypertonic citrate or University of Wisconsin solution. Plasma histamine concentration was unchanged from a control value of 23.2 +/- 2.6 ng/ml 15 min after reperfusion of grafts, whether fresh or stored for 24 h or for 48 h. Mucosal histamine levels in the grafts fell, however, from a control value of 371.0 +/- 22.9 ng/g tissue, first on storage then further after 15 min reperfusion. No differences were found in these parameters of histamine release between any of the preservation media. It is suggested that histamine may play a role in storage and reperfusion damage to small bowel transplants.

Reduced susceptibility to lipid peroxidation in cold ischemic rabbit kidneys after addition of desferrioxamine, mannitol, or uric acid to the flush solution.

Rabbit kidneys were stored for 24 hr at 0 degree C after single passage arterial flush with 30 ml of cold isotonic 0.9% sodium chloride (saline) solution alone or saline to which was added 12, 30, or 60 mM desferrioxamine, 1 or 3 mM uric acid, or 100 mM mannitol. They were then subjected to in vitro biochemical assay for evidence of free radical damage immediately after storage. Results were compared to those obtained with fresh, unstored kidneys. Levels of Schiff base fluorescence, diene conjugates, and thiobarbituric acid-reactive material were each significantly elevated in kidneys stored for 24 hr after flush with saline alone. These levels were in turn each significantly reduced by the addition of 60 mM desferrioxamine, 3 mM uric acid, and 100 mM mannitol to the flush solution. Likewise, glutathione redox activity fell in those flushed with saline alone, presumably in line with increased lipid peroxidation, but was restored to control levels by inclusion of the three scavenging agents.

Monitoring of surface mitochondrial NADH levels as an indication of ischemia during liver isograft transplantation.

Ischemia-reperfusion injury is a major cause of transplant dysfunction. One feature of this damage is mitochondrial dysfunction. The objective of this study was to determine whether surface fluorometric measurements of mitochondrial NADH can be made, and if the technique can detect differences in mitochondrial respiration between minimally stored 1 to 2 degrees C for 25 minutes (group 1, control) transplanted livers and those stored in hypertonic citrate at 1 to 2 degrees C (group 2) for 24 hours before transplantation. Measurements were made in livers isografted in 20 male Lewis rats. The technique is sufficiently sensitive to detect increased (nicotinamide-adenine dinucleotide (NADH) during dissection of hepatic vessels before ligation 0.52 +/- 0.04 (n = 14, P < .03) compared with the in situ exposed liver, 0.43 +/- 0.02 n = 14). Complete hepatic ligation resulted in a significant increase in NADH (1.22 +/- 0.10, n = 14), P < .0001) compared with hepatic artery ligation, which did not increase NADH levels. After storage, NADH levels increased (P < .02) but there was no significant difference between groups. In group 1, completion of portal vein (PV), suprahepatic vena cava (SVC), and descending vena cava anastomoses resulted in decreased NADH levels toward those after preparation of the vessels before ligation. However, there was a significant difference (P < .004) between the 25-minute and the 24-hour stored livers, 0.56 +/- 0.07 versus 0.23 +/- 0.04, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Desferrioxamine reduces susceptibility to lipid peroxidation in rabbit kidneys subjected to warm ischaemia and reperfusion.

Rabbit kidneys were clamped and subjected to warm ischaemia for 60 or 120 min then reperfused with blood for 60 min or for 24 hr. Treated rabbits received desferrioxamine at 15 or 50 mg/kg i.v. 15 min before reperfusion. Their kidneys were then removed and assayed for phospholipid Schiff base fluorescence (ex. 360 nm, em. 435 nm), diene and triene conjugates by UV spectrophotometry (240 nm and 268 nm respectively), for superoxide dismutase and for reduced and oxidised glutathione to provide an index of glutathione redox activity. All indices of lipid peroxidation were significantly elevated in untreated rabbits and glutathione redox activity was reduced. Treatment with desferrioxamine however effectively prevented these deviations and in many cases maintained them at the levels in fresh rabbit kidneys. These data provide further evidence that lipid peroxidation occurring during the reperfusion period is superimposed on the damage set up during warm ischaemia and may be preventable by administration of suitable therapeutic agents.

Increased susceptibility to lipid peroxidation in rabbit kidneys: a consequence of warm ischaemia and subsequent reperfusion.

Rabbit kidneys were clamped and rendered warm ischaemic (WI) in situ for 60 and 120 min. They were then either removed immediately after the ischaemic insult or after reperfusion with blood for 60 min or 24 hr. Homogenates were assayed for phospholipid-Schiff base fluorescence (Ex. 360 nm, Em. 435 nm) and for diene conjugate formation by u.v. spectrophotometry (240 nm) as indices of lipid peroxidation. No alteration in tissue levels of Schiff base was evident immediately after WI but when the homogenates were incubated at 37 degrees C for 90 min, the rate of peroxidation was significantly elevated compared to controls (P less than 0.02 after WI of 60 min and P less than 0.001 after 120 min of WI). These values were still further elevated after reperfusion with blood for 60 min and 24 hr (P less than 0.001). Diene conjugates were raised after WI alone and further still after reperfusion. Thus an early index of lipid peroxidation (diene conjugation) suggested peroxidative damage during the warm ischaemic period itself, whilst detection of Schiff bases was only possible after in vitro incubation of the tissue. Both indices of oxygen-derived free radical damage were increased after reperfusion in vivo with blood and may relate to the degree of tissue damage sustained during ischaemia and reflow.

Measurements of tissue viability in transplantation.

Near-infrared spectroscopy has primarily been used in monitoring changes in cerebral haemoglobin oxygenation and haemodynamics. However its use as a method for the assessment of tissue viability following transplantation has recently been explored experimentally in our laboratory. The ability to measure changes in oxygenation and perfusion during harvesting and following transplantation of organs or transfer of free and pedicled flaps potentially important in reconstructive surgery. We have found that near-infrared spectroscopy is extremely useful in detecting vaso-occlusive events and can accurately and reliably distinguish between arterial, venous or total occlusions. Venous congestion indicated by raised levels of deoxygenated haemoglobin with a concomitant increase in blood volume and the presence and magnitude of reactive hyperaemia are both easily recognizable features by near-infrared spectroscopy. We have shown that near-infrared spectroscopy measurements of venous congestion in kidneys (and other tissues) following prolonged storage correlate with medullary vascular congestion confirmed by angiographical and histological analysis of intrarenal perfusion. Clinically we have shown that flap perfusion can be improved by altering fluid replacement regimes and the addition of ionotropes. Cerebral near-infrared spectroscopy measurements in a liver transplant model showed statistically significant differences within minutes after the anhepatic phase in cerebral perfusion and oxygenation, between animals transplanted with ischaemically damaged livers compared to those isografted with minimally stored livers. Similarly we have found that near-infrared spectroscopy can be used as a monitor to assess the adequacy of fluid or blood replacement in haemorrhagic and hypovolaemic models. We believe that near-infrared spectroscopy provides a sensitive and reliable postoperative method for the assessment of tissue viability following the transfer of free and pedicled flaps and organs.