small intestinal function following syngeneic transplantation in the rat

JOURNAL OF SURGICAL RESEARCH 61, 379–384 (1996)ARTICLE NO. 0133

Small Intestinal Function Following Syngeneic Transplantation in the Rat1

DAVID L. SIGALET, M.D., NORMAN N. KNETEMAN, M.D.,* RICHARD N. FEDORAK, M.D.,†TARIK KIZILISIK, M.D.,* KAREN E. MADSEN, PH.D.,† AND ALAN B. R. THOMSON, M.D.†

*Departments of Surgery and †Medicine, University of Alberta, Edmonton, Alberta, Canada

Submitted for publication September 30, 1994

INTRODUCTIONImprovements in immunosuppression have led to

Recent reports of success with small intestinal trans-the use of small intestinal transplantation clinically.plantation and continued improvements in immunePrevious studies have suggested that the transplanta-suppression techniques have increased interest in thetion process and immunosuppression with cyclosporinuse of small bowel transplantation for treating patientsindependently affect small intestinal function. Thiswith the short bowel syndrome [1, 2]. Extensive litera-study describes the effects of syngeneic small intesti-ture has developed regarding the technical and immu-nal transplantation and cyclosporine in rats on intesti-

nal permeability and nutrient transport. Orthotopic nological aspects of intestinal transplantation [3–8].transplantation of the small intestine was performed However, relatively little is known regarding the func-between syngeneic (Lewis) rats. Transplanted animals tional capacity of the small intestine following trans-received chronic treatment with cyclosporine (10 mg/ plantation. Nutrient absorption from isolated loops [9],kg) or vehicle on alternate days. Sham operated con- in vitro measurements of nutrient uptake [10], and thetrols received treatment with vehicle. Animals were electrophysiological characteristics of transplantedfollowed for 60 days monitoring weight gain, feed in- bowel have been studied [6]. Intestinal function, astake, intestinal permeability, in vivo absorption of di- measured by these parameters, was uniformly reduced.etary fat and carbohydrate, and at sacrifice in vitro However, these studies were performed using hetero-transmural flux of 3-O-methyl-D-glucose. Weight gain, topically placed intestine not exposed to luminal nutri-feed intake, and absorption of fat and carbohydrate ents or using models where immune interactions couldfrom the diet were not altered by intestinal trans- occur. Since defunctioning the intestine, by itself, re-plantation alone; transplantation plus cyclosporine

duces functional absorptive capacity [11, 12], thesetreatment caused a slight reduction in dietary fat ab-studies cannot accurately establish the effect of smallsorption. Both the transplant and transplant plusintestinal transplantation on intestinal function. Incyclosporine groups demonstrated increased perme-previous work we found that cyclosporine (CsA) af-ability to 51Cr-EDTA and mannitol but not lactulose.fected nutrient absorption and permeability in non-Jejunal and ileal 3-O-methyl-D-glucose net transmuraltransplanted control intestine [13–15]. In addition, al-flux was decreased in both transplant and transplantlogenic intestinal transplants treated with cyclosporineplus cyclosporin groups. Intestinal transplantationdemonstrated a marked increase in permeability andand cyclosporine treatment reduce mucosal glucosedecrease in glucose and fat absorption [16]. The capac-transport and increase intestinal permeability. Theseity of the transplanted intestinal graft, under condi-altered transport characteristics could affect dietary

choices and the selection of immunosuppressive drugs tions of CsA immunosuppression, to absorb nutrientsduring clinical transplantation efforts, however, the and support growth would be an important consider-overall impact on animal well-being was minimal, and ation. Understanding the effect of the transplantationsupport the continued study of intestinal transplanta- and immunosuppression processes on intestinal func-tion for clinical application. q 1996 Academic Press, Inc. tion may affect such things as the choice of diet post-

ransplant, the use of permeability changes to monitorrejection, and may allow the development of therapiesto minimize such effects. This in turn would affect the

1 Dr. Sigalet was supported by the Alberta Heritage Foundation immunogenicity of the graft [17] and the prospects forfor Medical Research Clinical Fellowship (12-209), and the Canadianusing living related donors [2].Association of Gastroenterology/Merck Frosst Canada Incorporated

The present study examines the absorptive functionResearch Fellowship. Drs. Fedorak and Kneteman are supported byAlberta Heritage Foundation for Medical Research Clinical Investi- of orthotopically transplanted small intestine in synge-gatorships. Dr. Madsen is supported by a Medical Research Council neic (nonrejecting) rats treated with or without CsA.of Canada Fellowship. Further funding was provided by the Cana- We examined animal weight gain, feed intake, and adian Surgical Research Fund, the Medical Research Council of Can-

nutritional balance study to quantify nutrient absorp-ada, and the Edmonton Civic Employees’ Charitable AssistanceFund. tion in vivo. In vitro unidirectional 3-O-methyl-D-glu-

379 0022-4804/96 $18.00Copyright q 1996 by Academic Press, Inc.

All rights of reproduction in any form reserved.

AID JSR 4579 / m4784$$161 01-26-96 07:10:00 srga AP: Surg Res

380 JOURNAL OF SURGICAL RESEARCH: VOL. 61, NO. 2, MARCH 1996

injected subcutaneously in the nape of the neck with 10 mg/kg oncose transmural fluxes were examined to correlate inalternate days [16]. Control animals received equivalent volumes ofvivo parameters of nutritional well-being with in vitrosterilized medium chain triglyceride oil. CsA levels were determined

measurements of the absorptive function. Previous at sacrifice using a whole blood CsA specific monoclonal antibodystudies examined mucosal uptake of glucose following assay (Cyclo-trac SP 125I RIA kit, Incstar Corp., Stillwater, MN).CsA treatment in normal animals [13, 15], or measured Small intestinal transplantation technique. Small intestinal

transplantation was performed in two stages using previously de-the intestinal short circuit current following trans-scribed methods [5, 16, 23]. Following an overnight fast anesthesiaplantation with cyclosporine treatment [16]. Intestinalwas induced and maintained using halothane and oxygen via faceshort circuit current is an indirect measure of glucose mask. In the first stage the entire donor small intestine was isolated

transport, and may be altered by changes in permeabil- on a vascular pedicle that included the portal vein and infrarenality, sodium glucose cotransporter activity (NaGCT-1), aorta. The animal was then systemically anticoagulated with 150 U

of heparin intravenously, the aorta was ligated above the superioror other cellular metabolic processes affecting sodiummesenteric artery and flushed with 2–3 ml of iced heparinized Ring-flux [18, 19]. We sought to quantify more precisely theer’s solution and the donor small intestinal graft was quickly re-effects of the transplantation process, and the additive moved and stored in iced Ringer’s solution. The recipient’s infrarenal

effect of CsA treatment, on transplanted bowel, by mea- cava and aorta were isolated, and the donor small intestinal graftwas revascularized to the recipient by anastomosing the portal veinsuring glucose flux directly [19]. This was done usingand aorta in turn, end to side, using 10-O sutures. The proximala preparation of intestine, in which the serosa isjejunum of the donor small intestine was then closed, and the distalstripped, and the net flux from either mucosa to serosa,ileum was brought out as a stoma. The total warm ischemia time

or serosal side to mucosal side is quantified using radio- averaged 35 min, and was never longer than 42 min. The total coldlabeled 3-O-methylglucose (3-O-MG). This derivative ischemia time average 90 min. At this point the recipient’s native

small intestine was intact and functioning. The abdomen was closedof glucose is carried by the NaGCT-1 protein, but is notand the animal was immediately allowed free access to food andmetabolized by the cell. Net flux as measured with thiswater. The second stage of the procedure was done 1 week later. Amethodology, correlates with the sodium glucose co-repeat laparotomy was performed, and the recipients native small

transporter number, as determined by direct measure- intestine was resected from the ligament of Treitz to within 1 cm ofment with radiolabeled phlorizin [20, 21]. Small intes- the ileal–cecal junction. The transplanted donor small intestine was

then anastomosed in continuity end to end with the resected endstinal permeability was measured in vivo to assess theof the jejunum and ileum using interrupted sutures of 6-O silk andintegrity of the enterocyte mucosal barrier [22]. Wean internal stent of macaroni [16]. The abdomen was closed, and thehypothesized that transplantation, in the absence of animals were allowed free access to water. Food was reintroduced

rejection, and CsA treatment would independently af- 24 hr later.fect glucose transport by the transplanted intestine. In vivo nutritional balance studies. Fifty days following com-

mencement of the study the animals were placed in metabolic cages.After 5 days of preconditioning, they underwent a 3-day balance

MATERIALS AND METHODS study, with daily quantitative fecal collections. Total energy, protein,and carbohydrate content of feed and feces were determined usingstandard methods [25, 26] and nutrient absorption was calculatedAnimals. Male Lewis rats (300–320 g) were obtained from

Charles River Canada, St. Constant, Province of Quebec, and were directly.housed in individual plexiglass cages, with free access to chow (Tek- In vivo permeability studies. Following the balance study, ani-land Premium Lab Diet, Textron Corp., Madison, WI) and water. mals underwent assessment of intestinal permeability. After an over-Feed intake and body weight were monitored daily for the first 7 night fast, animals were gavaged with a test solution of 10 mCi ofdays then every other day until sacrifice. Weight gain is reported as 51Cr-EDTA in 2 ml of water. Urine was then collected for 6 hr; duringgain in body weight over the final 30 days of the 60-day study, follow- this time the animals were allowed free access to water but not toing recovery from surgery. Day/night cycles were 12 hr, and the food. After 2 days, the procedure was repeated using a test solutiontemperature was maintained at 20 { 27C. Complete blood counts of mannitol (Molecular Weight 182) and lactulose (Molecular Weightwere performed using a Coulter counter (M4-30, Coulter Electronics, 342), 100 mg of each in a total volume of 2 ml water. Urinary recoveryHialeah, FL), and serum electrolyte and creatinine levels were deter- of each marker was then measured using g-counting for 51Cr-EDTA,mined using a multistat analyzer (Il-Multistat III, Instrumentation and high performance liquid chromatography for the other markersLaboratories, Lexington, MA). Animal care was in accordance with [27, 28].the guidelines of the Canadian Council of Animal Welfare. The exper- In vitro unidirectional glucose fluxes. Following the permeabilityimental protocol used was approved by the Animal Welfare Commit- studies animals were sacrificed and intestine was obtained for intee of the University of Alberta. vitro studies. The intestine was split along the mesenteric border,

Experimental groups. For syngeneic transplantation Lewis rats segments of 2–3 cm were stripped of their serosa and underlyingwere used as donors and recipients. Three groups were compared: muscle layer, and were mounted in Ussing chambers as previously(1) Control: sham operation and subcutaneous injections of vehicle described [18–21]. Samples were taken from the jejunum just distal(medium chain triglyceride oil) on alternate days, (2) Transplant: to the ligament of Treitz, and unidirectional mucosal to serosal, Jmsorthotopic transplantation of the entire small intestine and subcuta- and serosal to mucosal Jsm fluxes were measured in duplicate. Simi-neous injections of vehicle on alternate days, and (3) Transplant plus larly portions of ileal tissue, just proximal to the ileocecal valve wereCsA: orthotopic transplantation of the entire small intestine and tested. Accordingly for each segment (jejunal and ileal) two measure-subcutaneous injections of CsA (10 mg/kg) in vehicle on alternate ments of Jms and two measurements of Jsm were obtained, and thedays. This dose of cyclosporine has been shown to allow survival net flux (Jnet) obtained by taking the difference of the averages.with good graft function in completely allogeneic models of orthotopic Normal Ringer’s solution with 20 mM fructose was used as thesmall intestinal transplantation in the rat, while the subcutaneous initial incubation solution. For measurement of unidirectional fluxes,dosing regimen allows for reliable levels within the clinically relevant 3-O-methyl-D-glucose (3-O-MG) [18, 19], was present at a concentra-range [15, 16, 24]. tion of 20 mM on both mucosal and serosal sides.

After a 20-min equilibration period a total of 5 mCi of 3H labeledCyclosporine. CsA powder (Sandimmune, Sandoz Pharmaceuti-cal Corp., Montreal, Province of Quebec) was dissolved in medium 3-O-methyl-glucose was added to either the mucosal or serosal side

of the chamber. At 10-min intervals samples were taken from thechain triglyceride oil (Mead Johnson, Ottawa, Ontario) at a concen-tration of 15 mg/ml, and sterilized by microfiltration. Animals were hot and cold sides of the chambers, pipetted into scintillation vials,


381SIGALET ET AL.: INTESTINAL FUNCTION AFTER SYNGENEIC TRANSPLANT

TABLE 2TABLE 1

Percent in Vivo Dietary Nutrient Absorption FollowingAnimal Characteristics Following Syngeneic SmallIntestinal Transplantation Syngeneic Small Intestinal Transplantation

TransplantTransplantControl Transplant plus CsA Control Transplant plus CsA

(n Å 8) (n Å 9) (n Å 10)(n Å 8) (n Å 9) (n Å 10)

Initial body 318 { 8.9 313 { 10.7 295 { 8.5 Total energy 84 { 0.4 84 { 0.5 83 { 0.2Fat 79 { 0.7 77.7 { 0.6 74.9 { 1.0*weight (g)

Body weight gain 105 { 4.4 113 { 8.7 108 { 8.0 Dry matterdigestibility 80 { 0.6 79.6 { 0.6 79.8 { 0.6(g/60 days)

Chow intakea 23.4 { 1.0 25.1 { 1.1 22.2 { 0.9(g/day) Note. Data is presented a percent nutrient absorbed from the diet;

mean { SEM. CsA: Cyclosporine A 10 mg/kg SQ alternate days.*P õ 0.05 relative to control.Note. Data are presented as mean { SEM. CsA: Cyclosporine A

10 mg/kg SQ alternate days.aOver final 30 days of study.

EDTA and a fall in the lactulose/mannitol ratio (Table3). CsA treatment of the transplanted group resulted in aand subsequently counted for activity of tritium, with appropriate

compensation for the sampling volume on the cold side. From this further increase in 51Cr-EDTA permeability. The passiveJms and Jsm were calculated in mmol/cm2 of epithelial tissue per permeability to lactulose was not affected by either smallminute as previously described [19, 20]. intestinal transplantation or CsA treatment.

To verify tissue integrity, the spontaneous transepithelial electri-cal potential difference (PD) was determined, and the tissue was

In Vitro Unidirectional Glucose Fluxesclamped at zero voltage by continuously introducing an appropriateshort-circuit current (Isc) with an automatic voltage clamp (DVC 1000 The effect of small intestinal transplantation andWorld Precision Instruments, New Haven, CT), except for 5–10 sec

CsA on in vitro 3-O-M glucose transmural fluxes areevery 10 min when PD was measured by removing the voltage clamp.shown in Fig. 1. Both small intestinal transplantationTissue conductance (G) was calculated from potential difference and

Isc according to Ohm’s law [18]. Tissue pairs were discarded if conduc- and small intestinal transplantation plus CsA treat-tance varied by ú20%. Tissue response to 5 mM theophylline was ment reduced net 3-O-M glucose transport approxi-used to confirm viability at the completion of the experiment [19]. mately 2-fold in both jejunum and ileum. This reduc-

Statistical analysis. Data are expressed as means { SEM, andtion in net 3-O-M glucose absorption was predomi-statistical analyses were performed by analysis of variance.nately due to a decrease in mucosal-to-serosal (Jms)3-O-M glucose movement in the transplanted groupRESULTSand an increase in serosal-to-mucosal (Jsm) 3-O-M glu-cose movement in the transplanted plus CsA-treatedAnimal Characteristicsgroup.

Survival of the two stage intestinal transplant opera-tion exceeded 85%, with no animals dying more than DISCUSSION5 days after an operative procedure. While chow intakevaried in the immediate postop period. Over the final These results show that while syngeneic (nonre-30 days of the study feed intake was similar in all jecting) orthotopic total small intestinal transplantsgroups (Table 1). Weight gain was similar in all groups. function well enough to allow normal body weight gain,CsA serum levels were similar between rats in the CsA-treated group (507 { 33 ng/ml).

TABLE 3In Vivo Nutritional Balance Studies

Intestinal Permeability Following SyngeneicAs shown in Table 2 absorption of fat from the diet Small Intestinal Transplantation

was not altered by transplantation alone, however,Transplantsmall intestinal transplantation plus CsA treatment

Control Transplant plus CsAreduced fat absorption by 8% relative to control (P õ (n Å 8) (n Å 9) (n Å 10)0.05). Total energy and dry matter digestibility werenot affected by small intestinal transplantation or CsA 51Cr-EDTA 2.1 { 0.2 2.7 { 0.1* 4.8 { 0.6*/

Mannitol 2.3 { 0.2 4.9 { 0.8* 5.3 { 0.4*(Table 2). The various treatment groups did not affectLactulose 1.2 { 0.5 0.9 { 0.3 0.9 { 0.2the complete blood count, serum electrolyte, or serumLactulose/creatinine values (data not shown). mannitol 0.61 { 0.02 0.20 { 0.01* 0.19 { 0.05*

Intestinal Permeability Note. Data is presented as percent recovery of orally administeredmarker in urine; mean { SEM. CsA: Cyclosporine A 10 mg/kg SQFollowing small intestinal transplantation permeabil- alternate days.

ity to both small and changed probes increased as evi- *P õ 0.05 relative to control./P õ 0.05 relative to transplant.denced by increased urinary recovery of mannitol, 51Cr-



percent absorbed from the diet, were not altered bytransplantation (Table 2). These results are similar tothose previously described [16, 29, 30]. Treatment ofthe transplantation group with CsA resulted in a smallfall in fat absorption. Previous studies have shownCsA-treated normal and small intestinal transplantedanimals to have decreased [15, 16, 30], unchanged [29],or increased fat absorption [31]. We would anticipatethat intestinal fat absorption would be impaired for upto 4–6 weeks following transplantation while lym-phatic reconstitution occurs [32]. Since the fat balancestudies in our rats were performed 8 weeks after trans-plantation it is unclear if lymphatic dysfunction con-tributed to our findings of fat malabsorption in a majorway. Alternatively, CsA may alter fat absorption di-rectly at the luminal or cellular level. It is unclear howthe combination of CsA and SIT might affect fat absorp-tion from the much higher fat diet typically consumedby humans. The present studies were performed usinga low fat (4% of calories) rat chow.

The main focus of this study was the determinationof the transepithelial flux of 3-O-M glucose, after trans-plantation. This method determines the net flux of 3-O-MG by measuring independently the mucosal-to-se-rosal (Jms) flux and the serosal-to-mucosal (Jsm). Con-ceptually, the Jms represents the facilitated diffusionof glucose from the intestinal lumen, as it is carriedacross the enterocyte membrane by the sodium glucosecotransporter (Na-GT1). Glucose uptake is coupledwith the uptake of a sodium ion, and facilitated by theextra to intracellular sodium concentration gradientmaintained by the sodium potassium ATPase pump ofFIG. 1. Effect of syngeneic small intestinal transplantation and

CsA on unidirectional transmural 3-O-methyl-D-glucose flux in jeju- the basolateral membrane. Thereafter, egress of glu-num (A) and ileum (B). Control (solid bar; sham operation treated cose from the cell is via a second carrier at the basolat-with vehicle), transplant (diagonal bar; syngeneic small intestinal eral membrane. The ‘‘rate limiting step’’ of this processtransplantation treated with vehicle), transplant/CsA (hatched bar;

is thought to be the initial transport across the entero-syngeneic small intestinal transplant treated with CsA, 10 mg/kgcyte membrane by the Na-GT1 carrier [33]. The Jsmalternate days. Jms, flux from mucosa to serosa; Jsm, flux from serosa

to mucosa; Jnet , numerical difference between Jms and Jsm (mmol/cm2/ represents the passive diffusion of glucose from thehr). Values are means { SEM and are itemized in Table 4. Trans- serosal side of the intestine to mucosa via transepithe-plant and transplant plus CsA treatment reduced 3-O-methyl-D-glu- lial ‘‘pores,’’ and intercellular gaps, typically controlledcose Jnet in both jejunum and ileum. In the transplant group this

by the tight junctions. The tight junctions may in factreduction in Jnet was due to a decrease in Jms. In the transplant plusbe dynamic, [34, 35], and may vary in permeabilityCsA group reduction in Jnet was due to an increase in Jsm. *P õ 0.02

compared to control. in response to stimuli such as hyperosmolar intestinalcontents, or enterocyte energy status [33] in order toallow absorption of nutrients by passive diffusion (so-there are significant reductions in jejunal and ileal

transmural unidirectional glucose absorption with called solute drag) with the solvent, water.Our results show that intestinal transplantationsome changes in intestinal permeability.

Body weight gain over 60 days was similar in sham causes a reduction in Jms, without any change in Jsm,and an overall net reduction in Jnet . Reviewing theoperated control, transplanted, and transplanted plus

CsA groups (Table 1). These results are similar to those steps in the pathway of the glucose transport from themucosa to serosa outlined above, transplantation maypreviously described and suggest that, in nonrejecting

syngeneic rats, the intestine following total orthotopic affect the number or activity of the sodium glucose co-transporter. Subsequent changes in transcellular diffu-small intestinal transplantation functions well enough

to maintain nutritional status relative to control ani- sion, such as the activity of the sodium extracellular–intracellular concentration gradient or the transportmals [16, 29]. Since chow intake was comparable be-

tween animal groups (Table 1), similarities in body via the second carrier at the basolateral membranehave not been shown to affect the rate of glucose fluxweight gain imply that in vivo nutrient absorption was

not significantly affected by transplantation or CsA ad- in other models, but could have been affected by thetransplantation process [33]. By analogy with otherministration. Indeed, in the present study, in vivo total

energy, fat and dry matter absorption, expressed as models of adaptation where glucose flux is altered in


383SIGALET ET AL.: INTESTINAL FUNCTION AFTER SYNGENEIC TRANSPLANT

TABLE 4

Effect of Transplantation and Cyclosporine on in Vitro 3-O-Methyl Glucose Fluxes

Jms Jsm Jnet PD Isc G

JejunumControl 1.52 { 0.14 0.48 { 0.04 1.04 { 0.14 1.33 { 0.2 36.2 { 3.2 27.6 { 1.5Transplant 0.87 { 0.11* 0.44 { 0.10 0.43 { 0.05* 1.39 { 0.2 26.7 { 2.9 20.1 { 1.5Transplant

plus CsA 1.14 { 0.1 0.69 { 0.08* 0.42 { 0.07* 1.03 { 0.1 26.6 { 4.3 26.9 { 2.9IleumControl 1.57 { 0.12 0.49 { 0.04 1.08 { 0.11 0.98 { 0.2 34.9 { 5.1 34.5 { 2.6Transplant 1.18 { 0.13 0.55 { 0.09 0.55 { 0.09* 1.46 { 0.1 33.9 { 4.1 26.9 { 3.0Transplant

plus CsA 1.43 { 0.2 0.80 { 0.09* 0.62 { 0.12* 1.05 { 0.2 23.8 { 2.8 31.2 { 3.9

Note. Values are means { SEM. Jms, flux from mucosa to serosa; Jsm, flux from serosa to mucosa; Jnet, numerical difference between Jms

and Jsm (mmol/cm2/hr); PD, potential difference (mV); Isc, short-circuit current (mA/cm2/hr); G, conductance (mS/cm2).*P õ 0.05 relative to controls.

response to various stimuli, ‘‘forward’’ glucose flux typi- an overall reduction in mucosal uptake of glucose aftercyclosporine treatment was noted. In our previouscally is controlled by altering the number and activity

of the sodium glucose cotransporter molecules [36]. The studies regarding the effects of allogeneic transplanta-tion on intestinal function, all animals were treatedmechanisms whereby the transplantation process

might affect this are not clear, but could relate to with cyclosporine, and the Brown Norway syngeneictransplant control groups showed a similar pattern tochanges in luminal transit of nutrients, local or sys-

temic hormonal factors, or the changes induced by the that described here, in which there was an increase inglucose induced short-circuit current following trans-dennervation process.

The results regarding the ‘‘back flux’’ or Jsm are some- plantation, with an apparent increase in permeability[16]. An identical pattern of increased Jms, with in-what surprising. Our previous work and this study sug-

gest that the permeability of the transplanted intestine creased Jsm overall reduction of Jnet has been observedin cyclosporine-treated normal animals [38].is increased to a variety of small probes such as manni-

tol and EDTA (Table 3) [14, 16]. However, the present This curious additive affect of cyclosporine in thisnonrejecting transplant model is difficult to under-results (Table 4) do not show an increase in Jsm follow-

ing transplantation, nor is there an increase in conduc- stand, but again may reflect changes in Na-GT1 activ-ity induced either by cyclosporine’s effects on cell divi-tance or a decrease in intestinal short-circuit current.

These results are similar to those we noted previously sion rate, expression of the Na-GT1 carrier, or alter-ations in more fundamental cellular processes such asin studies of allogeneic transplanted animals [16]. It

may be that the net absorption of probes over the entire sodium potassium ATPase activity [33]. Cyclosporinehas been noted to cause effects in isolated kidney cellsurface area of the intestinal mucosa may be sensitive

enough to detect changes that are not apparent when tubule lines, with apparent reductions in Na-GT1 ac-tivity [39].examining glucose flux in an isolated segment [37]. Al-

ternatively, changes in motility may affect transit time, In summary, syngeneic transplantation of the smallintestine results in subtle but significant changes inand thus alter apparent permeability [37]. However,

in our studies the ratio of absorption of lactulose to the function of the small intestine. These changes mayrequire consideration in attempts at clinical intestinalmannitol (Table 3) also changed, supporting the con-

cept that there was a true change in the permeability transplantation, and certainly appear to have an inter-action with cyclosporine therapy. In turn this may af-to the smaller mannitol probe. Examination of the ul-

trastructure of the small intestine, looking at changes fect other processes as the use of permeability changesto monitor rejection. Nevertheless, the general survivalin tight junctions, might be useful to clarify the link

between the transplantation process and the observed and well-being of the transplanted animals demon-strates that small intestinal transplantation is a prom-changes in permeability.

The results combining syngeneic small intestinal ising modality for investigation for clinical applica-tions.transplantation and cyclosporine treatment are inter-

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