Autotransplanted Dogs Research Articles

Pharmacokinetics and Pharmacodynamics of 15-Deoxyspergualin in a Canine Renal Allograft Model of Local Immunosuppression

Local immunosuppression is based on the rationale that one can simultaneously prevent rejection and reduce systemic side effects by administering appropriately chosen immunosuppressive agents directly into the allograft. We utilized a mongrel canine renal transplant model with a programmable, implantable pump/catheter system to estimate the first-pass extraction of 15-deoxyspergualin (DSG) during renal artery infusion and to compare the efficacy and toxicity of continuous intraarterial (ia) versus intravenous (iv) DSG delivery. Six autotransplanted dogs were given DSG by both iv bolus (1 mg/kg) and ia infusion (1.0 mg/kg/d). DSG was administered to allograft recipients by continuous ia infusion at 0.5 (n= 11) and 0.75 (n= 8) mg/kg/day and by continuous iv infusion at 0.5 (n= 12) and 0.75 (n= 6) mg/kg/day. Mean ± SD elimination half-life was 0.6 ± 0.1 hr, and the transplanted kidney removed as much as 55–88% (mean 66%) of locally infused DSG. When compared with untreated controls [mean survival time (MST) = 8 days], low-dose (0.5 mg/kg/day) DSG produced a significant antirejection effect when given ia (MST = 12 days;P= 0.04) but not iv (MST = 9 days;P= 0.09), with equivalent overall mean drug levels during normal renal function. However, two of the four longest-surviving animals in the ia group died from severe systemic toxicity, manifested by anorexia, diarrhea, leukopenia, and sepsis. High-dose (0.75 mg/kg/day) DSG significantly prolonged survival via both local (MST = 12 days;P= 0.04) and systemic (MST = 11 days;P= 0.02) routes, but half of the iv-treated dogs died from, and four of the longer-surviving ia-treated animals manifested signs of, systemic toxicity, with significantly higher mean drug levels in the iv group. DSG significantly suppressed vascular rejection at both doses when administered locally and systemically, dose-dependently affected the severity of tubulointerstitial rejection and graft edema, and was not nephrotoxic. Our autotransplant pharmacokinetic data overestimated the allografted kidney's ability to extract DSG during local infusion of slightly lower, but immunosuppressive, doses, so that death from systemic toxicity was not prevented and a direct survival benefit of ia vs iv therapy was not realized. Local DSG administration might be combined with other immunosuppressants to therapeutic advantage.

The effect of small bowel transplantation on the morphology and physiology of intestinal muscle: a comparison of autografts versus allografts in dogs.

The effects of acute (AR) and chronic rejection (CR) on intestinal smooth muscle that are responsible for the dysmotility following small bowel transplantation (SBTX) are incompletely understood. Jejunal and ileal specimens from normal control dogs (n=7), and autotransplanted dogs were examined at 7 days (n=6) and 1 (n=7), 3 (n=6), 6 (n=6), and 12 months (n=6). Allotransplanted dogs that developed AR (n=8) and CR (n=5) were examined for gross and microscopic morphology (muscle thickness, the number and size of myocytes, and inflammatory infiltrate), and for contractile and intracellular electrical function in vitro. Auto-SBTX did not alter morphology at any period, but contractile function was impaired at 7 days (73.6%) compared with normal intestine. Acute rejection did not influence myocyte number or size, but was associated with a prominent infiltrate of neutrophils and lymphocytes, and severely impaired contractile function (20.6%) compared with auto-SBTX controls. Acute rejection also significantly inhibited the amplitude of slow waves and of inhibitory junction potentials. Chronic rejection caused thickening of muscularis propria by both hyperplasia (175.5%) and hypertrophy (202.6%) accompanied by moderate inflammatory cell infiltrate compared with auto-SBTX controls. We conclude that the marked inflammatory infiltrate into the muscularis propria indicates that the graft muscle is injured by both acute and chronic rejection; impaired function of intestinal smooth muscle following SBTX results from both rejection and the injury associated with transplantation, and chronic rejection following SBTX is associated with both hyperplasia and hypertrophy of the muscularis propria.

Expression of the adult T-cell leukemia-derived factor, human thioredoxin, in the allotransplanted canine lung.

The relationship between the expression of adult T-cell leukemia-derived factor, human thioredoxin (ADF/TRX), and rejection in transplanted canine lungs was investigated in this study. Of a total 27 adult mongrel dogs, 24 underwent allotransplantation of the left lung with no immunosuppressant and the other three underwent autotransplantation of the left lung. Of the allotransplanted dogs, five were killed on postoperative day (POD) 1, five on POD 2, seven on POD 3, and seven on POD 5, while all three autotransplanted dogs were killed on POD 5. Histological examination was performed on the 24 allotransplanted left lungs (group A), 12 autologous right lungs (group B), and bilateral lungs of the three autotransplanted dogs (group C). The lung tissue was stained with anti-ADF antibody, and the high-ADF-producing cells (ADFh cells) in a randomly chosen field were counted as an index of ADF expression. As the signs of rejection in the group A lungs became more severe with time, the ADFh cells increased in number: 1.68 +/- 1.15, 6.08 +/- 3.44, 14.03 +/- 6.09, and 47.74 +/- 18.89, on PODs 1, 2, 3, and 5, respectively. However, the number of ADFh cells in the group B and group C lungs did not become significantly different from that on POD 1 in group A. These results suggested that ADF/TRX expression may be useful for the early diagnosis of rejection of transplanted lungs.

Site for unpurified islet transplantation is an important parameter for determination of the outcome of graft survival and function

Transplantation of unpurified islets into the liver, unlike that of purified islets, causes portal hypertension and coagulopathy. The aim of this project was to determine the most suitable alternative site for transplantation of unpurified pancreatic islets in autotransplanted dogs. Twenty-five female mongrel dogs were divided into 5 groups depending on the site of islet transplantation: liver (3), spleen (7), skeletal muscle (5), omental pouch (6), and renal subcapsule (4). Pancreatic digestion of the total pancreatectomized specimen was carried out by distension of the pancreas with 1.5 mg/mL collagenase suspended in 250 mL Hanks' balanced salt solution using a semiautomatic method. The total number of islets equivalent isolated from 25 dogs was 90948 ± 6053. Only islets > 60 μm in diameter were counted, and the mean islet equivalent transplanted per kg body wt was 6762 ± 429. Islet function was achieved with transplantation into spleen in 71%, omental pouch in 50%, and muscle in 20%, but none in the renal subcapsule or liver groups. Glucose tolerance test at 30 d showed a mean K Value (decline in glucose, %/min) of 1.94 ± 0.73, 0.79 ± 0.15 and 1.02 in the splenic, omental pouch and muscle groups, respectively. All animals in the liver group, 2 from the splenic group, and 2 from the renal subcapsule group died of diffuse bleeding. Four out of 5 dogs in the muscle group developed necrosis at the site of transplantation and the islets never functioned. This study demonstrates that in dogs, spleen and omental pouch appear to be suitable sites for transplantation of unpurified islets.

Site for unpurified islet transplantation is an important parameter for determination of the outcome of graft survival and function.

Transplantation of unpurified islets into the liver, unlike that of purified islets, causes portal hypertension and coagulopathy. The aim of this project was to determine the most suitable alternative site for transplantation of unpurified pancreatic islets in autotransplanted dogs. Twenty-five female mongrel dogs were divided into 5 groups depending on the site of islet transplantation: liver (3), spleen (7), skeletal muscle (5), omental pouch (6), and renal subcapsule (4). Pancreatic digestion of the total pancreatectomized specimen was carried out by distension of the pancreas with 1.5 mg/mL collagenase suspended in 250 mL Hanks' balanced salt solution using a semiautomatic method. The total number of islets equivalent isolated from 25 dogs was 90948 +/- 6053. Only islets > 60 microns in diameter were counted, and the mean islet equivalent transplanted per kg body wt was 6762 +/- 429. Islet function was achieved with transplantation into spleen in 71%, omental pouch in 50%, and muscle in 20%, but none in the renal subcapsule or liver groups. Glucose tolerance test at 30 d showed a mean K Value (decline in glucose, %/min) of 1.94 +/- 0.73, 0.79 +/- 0.15 and 1.02 in the splenic, omental pouch and muscle groups, respectively. All animals in the liver group, 2 from the splenic group, and 2 from the renal subcapsule group died of diffuse bleeding. Four out of 5 dogs in the muscle group developed necrosis at the site of transplantation and the islets never functioned. This study demonstrates that in dogs, spleen and omental pouch appear to be suitable sites for transplantation of unpurified islets.

Effects of jejunoileal autotransplantation on gastrointestinal regulatory peptides.

Plasma gastrointestinal hormones were measured before and during feeding in eight dogs, more than one year after total autotransplant of the entire jejunoileum, and in controls. At sacrifice, tissues were taken from the transplanted segment and intact bowel for measurement of hormone and enteric neuropeptide content. Gastrin levels were reduced in autotransplanted dogs (fasting 63% of control, incremental response 67% of control, both P < 0.05), reflecting the loss of acid inhibitory reflexes. Secretin and cholecystokinin responses were identical between the two groups. Postprandial levels of gastric inhibitory peptide (incremental response 175% of control, P < 0.005), insulin, and peptide YY (158% of control, P < 0.05) were elevated following denervation, the former suggesting more rapid gastric emptying while the latter may reflect malabsorption. The neurotensin meal response was obtunded by denervation (incremental response 43% of control, P < 0.05), providing evidence for a neural pathway for its release. Pancreatic polypeptide responses were identical between the groups, suggesting intact pancreatic innervation. Abnormal hormone secretion may contribute to the impaired fed motor responses seen following extrinsic denervation of the small bowel. In contrast, the neuropeptide content of the autotransplanted small intestine is normal, suggesting that extrinsic denervation has no long-term effects on peptide content of the enteric nervous system.

Mononuclear cells from dogs with acute lung allograft rejection cause contraction of pulmonary arteries.

Experiments were designed to determine whether or not leukocytes activated by acute pulmonary rejection cause contractions of isolated pulmonary arteries. Separate suspensions of (a) polymorphonuclear cells (> 95%) and (b) mononuclear cells (85% lymphocytes/10% monocytes/5% polymorphonuclear cells), respectively, were obtained from the arterial blood of four groups of adult male mongrel dogs: unoperated dogs (controls), dogs with single-lung autotransplants, dogs with rejecting single-lung allotransplants, and unoperated dogs treated with the same immunosuppressants as allotransplanted dogs. These suspensions were added to rings of control intralobar pulmonary arteries suspended in organ chambers for measurement of isometric force. The endothelium was removed mechanically from selected rings. No significant change in basal tension of pulmonary arterial rings occurred by adding suspensions of polymorphonuclear cells from any of the four groups of dogs. Significant cell-number-dependent increases in tension occurred with suspensions of mononuclear cells from unoperated dogs, autotransplanted dogs, and unoperated, medicated dogs. These increases in tension were less in rings with compared to those without endothelium. Addition of a synthetic analogue of L-arginine abolished this difference. Suspensions of mononuclear cells from rejecting allotransplanted dogs caused significantly greater contractions in rings with endothelium than those observed with suspended cells from either unoperated, autotransplanted dogs or unoperated, medicated dogs. Addition of superoxide dismutase plus catalase or an antagonist of endothelin-A receptors (BQ-123) reduced contractions in rings with endothelium but not in those without endothelium to suspensions of mononuclear cells from rejecting allotransplanted dogs. The results of this study suggest that mononuclear cells cause contraction of pulmonary arteries, which can be partially inhibited by endothelium-derived nitric oxide. However, if the mononuclear cells are activated by acute pulmonary rejection, contractions are no longer inhibited by the endothelium. Under conditions of rejection, contractions are mediated in part by oxygen radicals and endothelin(s).

The effect of cyclosporine and liver autotransplantation on bile flow and composition in dogs.

Following liver transplantation bile formation may be influenced by hepatic denervation and cyclosporine therapy. To better establish any effect of liver transplantation on bile secretion, 6 mongrel dogs were studied: 3 underwent liver denervation by a modified autotransplantation procedure and insertion of a Thomas cannula to create a chronic duodenal fistula; 3 others had cholecystectomy and the duodenal cannula placement without manipulating the liver. One month after surgery, two control studies were done, one week apart. Then oral cyclosporine was given in doses of 5, 15, and 50 mg/kg/day for consecutive 1-week periods each. Twice on each cyclosporine regimen, after 4 and 7 days of therapy, the common duct was cannulated and bile collected for 5 h; animals were awake and fasted. The first 3 h of bile collection established basal conditions; flow was then stimulated with consecutive hour-long taurocholate infusions at 1 and 2 mumol/kg/min. In all dogs, bile flow increased as the cyclosporine dose increased, under both basal and bile salt-stimulated conditions. The increased flow primarily resulted from increased bile salt-independent flow. Cyclosporine had no effect on bile salt, bilirubin, or cholesterol secretion. Phospholipid secretion, however, decreased significantly in a dose-related manner with increasing cyclosporine in the dogs with autotransplanted livers, but not in the nontransplanted dogs. This decrease in phospholipid secretion resulted in a significant increase in the calculated cholesterol saturation of bile. Thus, cyclosporine administered orally is not cholestatic but rather increases bile flow independent of any change in bile salt secretion. Cyclosporine reduced phospholipid secretion in autotransplanted dogs, possibly related to denervation of the liver. The resultant change in biliary composition may pose a risk factor for gallstone formation.

MODERATE EFFECT OF PREOPERATIVE BLOOD TRANSFUSIONS ON PANCREAS ALLOGRAFT SURVIVAL IN RATS AND DOGS

Treatment of type I diabetes by early pancreas transplantation requires the availability of a safe and effective transplantation technique. With the currently available immunosuppressive drugs it is difficult to obtain long-term pancreatic allograft survival. In this respect pancreas grafts compare unfavorably with heart or kidney grafts. Using a relatively simple and safe subcutaneous transplantation technique we investigated the effect of blood transfusions combined with low-dose immunosuppressive drugs in rats and dogs in order to attain an immunosuppressive schedule of low toxicity. Subcutaneous pancreas transplantation appeared to be a feasible technique, with long-term graft survival in syngeneically transplanted rats and autotransplanted dogs. Only a moderate prolongation of pancreatic allograft survival by blood transfusions was demonstrated in both models. In rats one or three preoperative donor-specific blood transfusions significantly prolonged pancreas graft survival to 23 +/- 15 and 29 +/- 15 days, respectively, compared with 12 +/- 2 days in untreated controls. Low-dose cyclosporine (15 mg/kg on the day of operation) led to improved graft survival in nontransfused recipients (17 +/- 4 days), however, this treatment could not further prolong graft survival in transfused animals (34 +/- 20 days). In dogs, treated postoperatively with azathioprine and prednisolone, three preoperative third-party blood transfusions led to 29 +/- 19 days of pancreas graft survival, which was not significantly different from nontransfused controls (17 +/- 5 days). These results indicate that, in rats as well in dogs, pancreatic allografts are less sensitive to the immunomodulating effect of blood transfusions than heart and kidney grafts.

THE PHARMACOKINETIC ADVANTAGE OF LOCAL 6-MERCAPTOPURINE INFUSION IN A CANINE RENAL TRANSPLANT MODEL1,2

In light of recent technologic advances, we developed a canine renal allograft model utilizing implantable, programmable infusion pumps and biocompatible catheters to reexplore the concept of local immunosuppression. Thirteen mongrel dogs underwent bilateral nephrectomy and autotransplantation of 1 kidney via end-to-end renal-iliac artery and end-to-side renal-iliac vein anastomoses. The proximal end of an infusion catheter directed into the iliac artery was tunneled to a subcutaneously placed programmable pump. A second, sampling catheter was placed with its tip in the iliac vein just proximal to the venous anastomosis. During a period of i.a. infusion of heparinized saline ranging from 19 to 63 days, serum creatinine remained normal in all but 1 animal, which developed pyelonephritis and catheter-tip perforation of the iliac artery. No cases of arterial thrombosis or catheter migration were observed at necropsy. In 7 additional autotransplanted dogs, simultaneous iliac vein and systemic (jugular vein) concentrations of 6-mercaptopurine (6-MP), the major immunosuppressive metabolite of azathioprine, were determined during a continuous 24-hr i.a. infusion (10 mg/kg/24 hr). Following termination of the infusion, 10 mg/kg 6-MP was administered to the same 7 dogs as an i.v. bolus, and systemic drug concentrations were determined over a 4-hr period. Mean +/- SE total-body clearance and elimination half-life were 887 +/- 159 ml/min and 1.4 +/- 0.2 hr, respectively, in the i.v. bolus study, indicating that 6-MP is rapidly cleared from the systemic circulation. Unexpectedly, the kidney removed as much as 60-95% of locally infused 6-MP, reducing the amount of active drug entering the systemic circulation to 5-40% of that which would be present during an i.v. infusion of the same dose. According to the principles governing the advantages of i.a. infusions, these data demonstrate that 6-MP can be infused intrarenally to produce both a 4-fold increase in drug concentration within the kidney and an 80% decrease in systemic drug delivery when compared to same-dose i.v. administration. The overall result is the presence of a 30-fold gradient between local and systemic drug concentrations during intrarenal 6-MP infusion. We conclude that i.a. infusion of an immunosuppressive agent is technically feasible with preservation of renal function, and that 6-MP can be delivered locally in a canine model with great pharmacokinetic and potential therapeutic advantage.

Metaiodobenzylguanidine [131I] scintigraphy detects impaired myocardial sympathetic neuronal transport function of canine mechanical-overload heart failure.

In heart failure secondary to chronic mechanical overload, cardiac sympathetic neurons demonstrate depressed catecholamine synthetic and transport function. To assess the potential of sympathetic neuronal imaging for detection of depressed transport function, serial scintigrams were acquired after the intravenous administration of metaiodobenzylguanidine [131I] to 13 normal dogs, 3 autotransplanted (denervated) dogs, 5 dogs with left ventricular failure, and 5 dogs with compensated left ventricular hypertrophy due to a surgical arteriovenous shunt. Nine dogs were killed at 14 hours postinjection for determination of metaiodobenzylguanidine [131I] and endogenous norepinephrine content in left atrium, left ventricle, liver, and spleen. By 4 hours postinjection, autotransplanted dogs had a 39% reduction in mean left ventricular tracer accumulation, reflecting an absent intraneuronal tracer pool. Failure dogs demonstrated an accelerated early mean left ventricular tracer efflux rate (26.0%/hour versus 13.7%/hour in normals), reflecting a disproportionately increased extraneuronal tracer pool. They also showed reduced late left ventricular and left atrial concentrations of tracer, consistent with a reduced intraneuronal tracer pool. By contrast, compensated hypertrophy dogs demonstrated a normal early mean left ventricular tracer efflux rate (16.4%/hour) and essentially normal late left ventricular and left atrial concentrations of tracer. Metaiodobenzylguanidine [131I] scintigraphic findings reflect the integrity of the cardiac sympathetic neuronal transport system in canine mechanical-overload heart failure. Metaiodobenzylguanidine [123I] scintigraphy should be explored as a means of early detection of mechanical-overload heart failure in patients.

Long-term daily study of blood volume in cardiac autotransplanted dogs.

Cardiac transplantation is followed by the interruption of afferent nerves to the heart. Knowing that some of the afferent nerves are responsible for the homeostasis of the blood volume, we undertook a serial and long-term study of the blood volume in 25 dogs with denervated hearts. The animals were autotransplanted in order to eliminate repercussions linked to rejection and to its treatment. To discern the effects of surgery and of extracorporeal circulation from those of denervation, a group of 11 control dogs was operated upon and subjected to a period of extracorporeal circulation. In both groups, serial and long-term studies of blood volume were carried out daily with 131I-labeled albumin. Analysis of the results demonstrated that in the hours following surgery, blood volume is significantly decreased by 11% in the control group and by 22% in group 2. By the 5th postoperative day, the blood volume had increased gradually to attain normal values in both groups. At the 2nd postoperative week, the total blood volume remained normal in the control group, whereas blood volume had increased by 5.7% in the autotransplanted dogs, this being due to a 38% increase of the plasmatic phase. This increment persisted from the 14th to the 42nd postoperative day and attained 7.4%. Our conclusion is that the variations in blood volume during the 1st postoperative week in the autotransplanted heart are inherent in surgery and in extracorporeal circulation. Afterwards, the hypervolemia shown in the transplanted dogs is secondary to cardiac denervation.

Acute Hypercalcemia and Cardiac Autotransplantation in Dogs: Long-Term Hemodynamic Adaptability

Cardiac autotransplantation (excision and reimplantation) is a unique model that isolates totally the cardiac afferent and efferent neural pathways and results in hemodynamic misadaptability to many provocative tests. Since the cardiovascular response to acute hypercalcemia is modulated by numerous factors among which the autonomic innervation plays a major role, the hemodynamic response to bolus administration of calcium gluconate was compared in normal and cardiac autotransplanted dogs. Twenty-two animals underwent an autotransplantation while a sham procedure was performed in 18 animals. Each dog was equipped with an electromagnetic flow probe positioned around the ascending aorta and with central venous and aortic catheters. Hemodynamic data were collected daily during 1 month, before and during rapid intravenous administration of calcium gluconate (0.90 mEq). Baseline hemodynamic studies indicate that for both groups myocardial failure is evident in the immediate postoperative period; despite progressive recovery, the autotransplants always show lower cardiovascular performance. Calcium administration elicits transient positive inotropism, which is more important in presence of myocardial failure; this is true for both control and autotransplanted dogs. In the early postoperative period, hemodynamic adaptability to this stress is impaired in the autotransplants. However, long-term results indicate that minimal differences subsist over time in response to calcium administration, and when they are observed, they result from interferences in baroreceptor regulation and reflexes.

Long-term normoglycemia in pancreatectomized dogs transplanted with frozen/thawed pancreatic islets

Storage of pancreatic islets by cryopreservation would greatly facilitate a large scale program of clinical islet transplantation. We report success on long-term follow-up with autotransplantation of frozen/thawed canine pancreatic fragments. Total pancreatectomy and islet isolation by collagenase ductal perfusion and mechanical disruption preceded either acute autotransplantation or cryogenic preservation prior to autotransplantation. Cryopreservation was by dimethylsulfoxide equilibration, cooling at 0.25 °C/min to −75 °C, storage in liquid N 2 and thawing at 3.5 °C/min. Four of five acutely autotransplanted dogs remained normoglycemic for 20 months, with three of four maintaining normal K values on intravenous glucose tolerance test (IVGTT) and nondiabetic values on oral GTT. Four of four dogs transplanted with frozen/thawed islets remained normoglycemic for 15 months with three of four maintaining nondiabetic IV GTT K values and normal oral GTTs for 15 months. Both acutely transplanted and frozen/thawed islets are capable of maintaining long-term metabolic control. Cryopreservation preserved viability of sufficient canine pancreatic islets to reverse diabetes with autotransplantation. Function of the frozen-thawed islets showed minimal deterioration during a followup of 15 to 18 months.

Small intestinal transplantation

The purpose of this study was to determine whether small intestinal transplantation could be considered as an alternative in the treatment of patients suffering from the short-bowel syndrome. The site of absorption of oral cyclosporine A was determined as were the changes that follow small intestinal transplantation. The interactions between the lipophilic cyclosporine A molecule and fat emulsion solutions used for total parenteral nutrition were investigated. Finally, a technique for harvesting the entire small bowel in man was developed. The absorption of oral cyclosporine A in normal dogs, and in bowel-resected, autotransplanted, and allotransplanted dogs was determined. Cyclosporine A levels were monitored in all animals. This demonstrated that cyclosporine A is absorbed through the small bowel and carried through the lymphatics; that absorption is decreased to 40 percent of normal after autotransplantation or allotransplantation without rejection. Rejection further hampers cyclosporine A absorption. Administration of olive oil alone enhances absorption of cyclosporine A. We also administered cyclosporine A IV to five dogs, with and without a concomitant infusion of fat emulsion solution (Intralipid). No changes in plasma cyclosporine A levels, in the clearance of cyclosporine A, or in the in vivo distribution of cyclosporine A were noted. Finally, dissections in six cadavers and in four brain-dead organ donors were performed, and a reproducible technique for harvesting the small bowel in man was established. In selected patients with the short-bowel syndrome, small intestinal transplant may be considered as an alternative therapy to home total parenteral nutrition.

CYCLOSPORINE ABSORPTION IN INTESTINAL TRANSPLANTATION

The absorption of oral cyclosporine (CsA) was studied in a canine small intestinal transplantation model. Absorption of CsA was almost absent in bowel-resected dogs. Autotransplanted dogs showed a persisting malabsorption of CsA (mean peak of 687 +/- 348 ng/ml vs. 1683 +/- 154 ng/ml in control dogs). Allotransplanted dogs with normal graft histology showed a similar malabsorption (mean increase in CsA level: 833 ng/ml), whereas allotransplanted dogs with rejection of the graft showed a markedly decreased absorption (mean increase: 368 +/- 31 ng/ml). In two autotransplanted dogs pretreated with olive oil alone, CsA absorption increased over four weeks to a mean peak of 2215 +/- 5 ng/ml. We conclude that oral CsA is absorbed through the small intestine. Absorption of CsA is decreased after autotransplantation and allotransplantation, and rejection of the graft impedes it further. Regular administration of olive oil alone enhances absorption of oral CsA in a canine model.

Functional monitors of rejection in small intestinal transplants

Absorption of cyclosporine and uptake of radiolabelled glucose by the transplanted small intestine in the dog was investigated to develop physiologic markers of rejection. Cyclosporine in olive oil was given orally, and glucose-14C was instilled into an isolated pouch constructed from the transplanted jejunum. Biopsies were simultaneously obtained from an isolated pouch made from the transplanted ileum. The absorption data were correlated with the histologic findings. Absorption of cyclosporine was of the same magnitude in autotransplanted dogs as it was in allotransplanted dogs with a normal graft. Absorption of cyclosporine in allotransplanted dogs with histologic signs of rejection was significantly reduced. Peak uptake of glucose-14C was noted 5 to 10 minutes after instillation of the isotope in autotransplanted and allotransplanted dogs with a normal graft. Allotransplanted dogs undergoing rejection had a delayed appearance of peak uptake and significantly reduced absolute uptake. In conclusion, absorption of cyclosporine and uptake of radiolabelled glucose can be utilized as functional monitors of intestinal allograft rejection.

The urodynamic patterns and pathophysiology of the canine allotransplanted upper urinary tract.

The urodynamic patterns of pelvic pressure, pelvic volume and frequency of ureteral peristalsis and the pathology of the upper urinary tract after renal allotransplantation were investigated in 41 dogs. The findings were compared with previous measurements of both normal and renally autotransplanted dogs. The urodynamic patterns of the allotransplants were unchanged and not influenced by variations of renal function or degree of rejection. Morphologic alterations of collagen infiltration in the smooth muscle tissue changed the viscoelastic behaviour of the system. Finally, the results support that myogenic impulses govern the urinary transport from the canine kidney to the bladder.

Effect of ATP-MgCl2 treatment on kidney preservation and on recovery of graft function.

The effect of ATP-MgCl2 treatment was investigated on the biochemical changes of preserved kidneys and on the functional recovery of hypoxically damaged and autotransplanted canine kidneys. We observed that ATP-MgCl2 administered before or during simple hypothermic storage did not protect the integrity of preserved kidney cells, as measured by enzyme wash-out (LDH and NAG) or by lactate release. If the compound was administered after 120 min or 180 min clamping of the renal artery, the solitary kidney showed a faster regeneration as measured by changes in serum creatinine level. The survival rates were significantly higher in the treated groups. Without warm ischemia of the kidney all of the autotransplanted dogs survived after surgery. After 60 min of warm ischemia the mortality rate was 100%, and the mean survival time in average 5 days. If ATP-MgCl2 was administered after the 60 min of warm ischemia, an improved recovery of the graft function was observed