Sodium-dependent d -glucose transport in brush-border membrane vesicles after massive distal small bowel resection in the rat

GASTROENTEROLOGY

1987;92:1987-93

Sodium-Dependent D-Glucose Transport in Brush-Border Membrane Vesicles After Massive Distal Smal1 Bowel Resection in the Rat W. C. KWAN,

G. A. QUAMME,

and H. J. FREEMAN

Department of Medicine, University of British Columbia Hoipital, Vancouver, British Columbia, Canada

Massive smal1 intestinal resection in both structural and functional

in the rat results

changes in the residual smal1 bowel. Sodium-dependent o-glucose transport was examined in brush-border membrane vesicles derived from the proximal smal1 bowel mucosa of male Sprague-Dawley rats 2 and 6 wk after a 66% distal jejunoileal resection or jejunoileal transection. Kinetic characteristics for the Iowafinity, high-capacity system and high-afinity, lowcapacity system were dejïned with rapid jïltration under conditions of a zero-trans, 100 mM cis-NaSCN gradient. Mucosal weight, protein, and deoxyribonucleic acid content were increased in the residual intestinal segment compared to transected controls and morphometric studies revealed increased villus and crypt heights as wel1 as an increased mitotic index. Postresection mean kinetic parameters for pglucose transport at 2 wk (low-afinity system: K,, 177.5 ? 45.1 PM; V,,,, 3.73 + 0.99 nmol . mg proteiñl . min-‘; and high-affnity system: K,, 6.2 0.12 k 0.06 nmol . mg + 1.9 PM; V,,,, proteiñ’ min-‘) and 6 wk (low-affnity system: K,, 267.8 * 83.1 PM; V,,,, 0.06 k 0.01 nmol . mg proteiñ’ . min-‘; and high-affnity system: K,, 6.5 k 1.1 PM; V,,,, 0.06 If-0.01 nmol mg protein-’ min-‘) were similar to values posttransection at 2 wk (low-affnity system: K,, 280.4 ? 3.05 ? 0.32 nmol . mg 53.7 PM; V,,,, proteiñ’ min-]; and high-affnity system: K,, 9.1 -t 1.3 PM; Vmax> 0.17 k 0.01 nmol . mg Received September 26, 1986. Accepted January 12, 1987. Address requests for reprints to: Dr. Hugh Freeman, Gastroenterology, ACU F-137, University of British Columbia Health Sciences Centre Hospital, 2211 Wesbrook Mall, Vancouver, British Columbia, Canada V6T 1W5 This work was supported by a research grant to Dr. Freeman from the Canadian Foundation for Ileitis and Colitis, Toronto, Canada. 0 1987 by the American Gastroenterological Association 0016-5085/87/$3.50

and the Health

Sciences

Centre

protein-’ min-‘) and 6 wk (low-affnity system: +- 17.5 PM; V,,,, 4.69 + 0.23 K l?l, 271.7 nmol . protein-’ . min-‘; and high-afinity system: K,, 10.6 k 4.2 PM; V,,,, 0.16 -+ 0.09 nmol . mg protein-’ . min-‘). These kinetic data suggest that the hyperplastic response in adapting proximal smal1 bowel after distal resection is accompanied by a persistente of the membrane functional characteristics for both sodium-dependent o-glucose transport systems despite an altered pattern of enterocyte proliferation and differentiation.. Massive smal1 intestinal resection in experimental animals and humans leads to structural and functional changes in the residual smal1 bowel. This intestinal adaptive response appears to involve a complex interaction between luminal, neurohumoral, and ether putative factors. This subject has been extensively reviewed elsewhere (1~). Morphologie alterations in the rat include lengthening of the smal1 intestinal crypts and villi as wel1 as an enhanced mitotic index; these changes appear to correlate with the length of smal1 bowel removed (3,4). Although methods for morphometric measurements may be controversial (51, hyperplasia rather than hypertrophy appears to account for the major morphologic and proliferative changes that occur in the residual smal1 intestine after resection. In addition, total mucosal enzyme activities are generally increased if expressed on a unit intestinal length basis (6,7), but their specific activities (i.e., based on milligrams of protein) remain unchanged (7-9) or decreased (9). The latter phenomenon has been explained on the basis of enterocyte immaturity in the adapting smal1 intestine (9). In vivo absorption of glucose and ether nutrients, studied by perfusion techniques, expressed in terms of unit intestinal Abbreviation

used

in this paper:

K,, Michaelis

constant.

1988

KWAN ET AL.

GASTROENTEROLOGY Vol. 92, No. 6

length have uniformly been increased (3,9-11). Presumably, as for enzyme activities, there is little or no change in the transport capability per unit membrane, but this has been difficult to examine. Purified brush-border membrane vesicles permit examination of transport events dissociated from internal compartmentalization, intracellular metabolism, and other luminal factors (i.e., secreted glycoproteins); moreover, measurements can be based on protein content of the brush-border membrane (12). Previous studies have provided good evidente for a multiplicity of o-glucose transport processes in the smal1 intestine (1%lí’), and these can be defined by differences in kinetic parameters, sodium stoichiometries, and differential sensitivities to phlorizin inhibition (15). Recent studies from our laboratory (18) have also demonstrated two apparently distinct sodiumdependent n-glucose transport systems in rat smal1 intestinal brush-border membrane vesicles: a lowaffinity, high-capacity system and a high-affinity, low-capacity system. These were defined by kinetic analysis of n-glucose uptake measured by rapid filtration techniques (19). Additionally, age-dependent changes in glucose transport kinetics for both jejunal and ileal membranes were evident. The high-affinity system was more abundant in proximal than distal smal1 bowel and with increasing age, a low-affinity system appeared in distal smal1 bowel resulting in the presence of both carriers along the length of the smal1 intestine (18). The use of isolated brush-border membrane vesicles can contribute to our understanding of the functional alterations that may result from intestinal injury, i.e., resection. Menge et al. (20) studied the functional properties of rat ileal mucosal membrane vesicles after proximal smal1 bowel resection; they observed no differente in the “overshoot phenomenon.” However, kinetic analysis was not performed; thus, it was not possible to define specific transport changes that might occur in adapting intestine. The present study extends these earlier studies in residual smal1 intestinal brush-border membrane vesicles by examining the kinetic parameters of n-glucose uptake 2 and 6 wk after resection and suggests that functional changes in the sodiumdependent n-glucose transport assembly are similar in resected rats and transected control animals. Materials Animals

and Methods and Diet

Male Sprague-Dawley rats weighing 200-250 g were maintained on Rat Chow (Ralston Purina, St. Louis, Mo.); water was allowed ad libitum. Relative humidity and environmental air temperature were constant and a 12-h

light-dark cycle was maintained. Rats were randomlv assigned to two groups: transection controls or distal resection. After surgery, animals were weighed on a weekly basis.

Surgery Al1 animals were anesthetized with an intraperitoneal injection of sodium pentobarbital (65 mg/kg body wt) after a 24-h fast. Midline laparotomy was performed with delivery of the smal1 intestine onto a salinesoaked gauze. In the transected group, the length of intact jejunum and ileum was measured and the smal1 intestine was transected midway between the ligament of Treitz and the junction of the large intestine followed by end-to-end reanastomosis. In the resected group, the smal1 bowel was first divided 4 cm proximal to the ileocecal valve; the length of the remaining ileum and jejunum was measured and two-thirds was resected followed by end-to-end reanastomosis. Measurements of the intestinal length were obtained from the mesenteric border with a standardized length of plastic tubing. Al1 anastomoses were performed with a 5-0 Dexon polyglycolic suture (American Cyanamid Co., Pearl River, N.Y.). After surgery, al1 animals were given dextrose in water (5% wt/vol) for 36 h before Rat Chow and tap water were reinstituted. Methods used for smal1 bowel resection and transection in our laboratory have been previously reported (21).

Vesicle Preparation Brush-border membrane vesicles were prepared from the smal1 intestine by a technique similar to that previously described (19)and modified from Kessler et al. (22). The animals were anesthetized with an intraperitoneal injection of sodium pentobarbital. The abdomen was opened and the smal1 bowel from the ligament of Treitz to the anastomotic site was removed and flushed with 50 ml of ice-cold physiologic saline. The lengths of the intestinal segments were measured with a 10-g weight attached to one end, and tissues were taken for histology from the midportion. The intestine was cut open lengthwise and the mucosa was gently scraped off with a glass slide and placed in ice-cold buffer containing 300 mM e-mannitol, 5 mM ethyleneglycol-bis (/3-aminoethylether)-N,N’-tetraacetic acid and 0.1 mM phenylmethylsulfonylfluoride in 12 mM Tris-HCl, pH 7.1. Mucosal scrapings from 2-3 animals were pooled for each experiment. The mucosal scrapings (about 5 g/20 ml buffer) were homogenized with a glass/Teflon tissue homogenizer (Wheaton overhead stirrer, Wheaton Scientific, Millville, N.J.) for 3 min at half the maxima1 setting. Ice-cold water was then added to the homogenate to bring the final volume to 200 ml. This was further homogenized with a polytron (model PT 10-35, Brinkmann Instruments Inc., Westbury, N.Y.) at a setting of 5 for 20 s. One molar MgS04 was added to the homogenate to produce a final concentration of 10 mM MgSO+ After stirring for 10 min at 4”C, the solution was centrifuged at 3440 g for 10 min and the resulting supernatant containing brush-border membrane

June 1987

vesicle material was centrifuged at 35,300 g for 25 min. The resulting pellet was resuspended in 20 ml of ice-cold buffer, 60 mM o-mannitol, and 1.5 mM ethyleneglycol-bis (/3-aminoethylether)-N,N’-tetraacetic acid in 12 mM TrisHCl, pH 7.1, using a tissue homogenizer and then centrifuged at 35,300 g for 25 min. The brush-border membrane pellet was resuspended in 20 ml of ice-cold buffer, 300 mM o-mannitol, and 10 mM Tris-I-IEPES, pH 7.4, and then centrifuged at 35,300 g for 30 min. The final brush-border membrane pellet was suspended in 300 mM o-mannitol, 10 mM Tris-HEPES, pH 7.4, with a syringe and 25gauge needle to a concentration of about 6-10 mg vesicle protein per milliliter. The vesicle preparation was allowed to stand at room temperature for 15 min before use. Al1 uptake measurements were performed within 3 h. Aliquots of mucosal homogenate and final vesicle suspensions were rapidly frozen at - 70°C and stored for enzyme, protein, or deoxyribonucleic acid (DNA) analysis, or any combination thereof.

Uptake Measurements The rapid filtration technique was used to determine sodium-dependent o-glucose uptake into the vesicles (14,22). In brief, 50 ~1 of incubation medium kept at 21°C was pipetted into the bottom of a 12 x 75-mm polystyrene test tube and 10 ~1 of vesicle suspension was spotted on the side wal1 near the bottom. The reaction was initiated by mixing with a Vortex that activated a timer (GraLab model 450, Gralab, Centerville, Ohio). The reaction was terminated after 5 s by delivering 5 ml of ice-cold stop solution into the test tube. The mixture was then rapidly filtered on a prerinsed 0.45~Pm pore size cellulose nitrate filter (Millipore Corp., Bedford, Mass.). The test tube was rinsed once with 5 ml of cold stop solution and rapidly filtered with the vesicles. The filters were washed with another 5 ml of cold stop solution, air-dried, dissolved in 2.5 ml of Filter Count (Packard Instrument Co. Inc., Downers Grove, Ill.), and counted with standard liquid scintillation techniques using a Beckman model LS 7800 counter (Beckman Scientific Instruments, Irvine, Calif.). Corrections were made for radioactivity bound to the filters in the absente of vesicles as wel1 as for sodium-independent uptake through the glucose concentrations studied in both resected and transected animals. Uptakes were expressed as nanomoles of o-glucose per milligram of membrane protein per minute. Al1 measurements were performed at least three times. The uptake was determined to be linear to at least 8 s for the range of glucose concentrations used and was considered to be an adequate estimate of the “initial” rate of substrate transport. The incubation medium consisted of 60 mM o-mannitol, 120 mM NaSCN, 10 mM Tris-HEPES, pH 7.4, and varying o-glucose concentrations. When [H3]o-glucose with specific activities of 20-30 Ci/mmol was added to the incubation medium, the final glucose concentration was calculated to range from about 1 to 400 PM. Approximately 1.5 x 106 cpm were available per 50 ~1 of medium.

MEMBRANETRANSPORTAFTER BOWEL RESECTION

Kinetic

1989

Analysis

Kinetic constants were calculated using the Michaelis-Menten equation with a nonlinear least-squares best fit for saturation isotherm assay data assuming two independent sites (Lundon Software, Cleveland, Ohio).

Other Measurements Protein was determined by the method of Lowry et al. (23) after treatment of the samples with 5% sodium dodecyl sulfate (wtivol), using bovine serum albumin as the protein standard. Deoxyribonucleic acid was determined with calf thymus DNA as the standard (24). The purities of the final vesicle suspensions were assessed by sucrase activity according to the method of Dahlqvist (25); a consistent 7-lO-fold enrichment was observed in the final pellet compared to the crude homogenate for both transected and resected animals. The smal1 intestinal biopsy specimens were fixed in Bouin’s solution, embedded in paraffin, sectioned parallel to the villus-crypt axis, and stained with hematoxylin and eosin. Crypt and villus heights were measured and the number of mitoses per crypt was counted. Eight measurements were obtained from each biopsy specimen. Statistical

Analysis

In the text and figures, mean values with standard errors are presented and statistical significante was calculated using an unpaired Student’s t-test.

Results Animal

Weights

Although there was an expected initial difference in body weight 1 wk after surgery, mean weight gains on a weekly basis were similar in transected and resected animals over the period of the study. Mean weights (*SE) at the time of the transport studies in resected compared to transected control rats were as fellows: 2 wk, 266 -+ 8 g versus 314 rt 10 g; and 6 wk, respectively.

405

+

10 g versus

455

+

14 g,

Mucosal Tissue Parameters Mucosal tissue parameters

are shown in Table

1. At 2 and 6 wk after surgery, the mucosal weight (p < 0.05), protein (p < 0.05), and DNA content (p < 0.05) expressed per unit intestinal length were significantly higher in resected than transected control rats. There was no differente, however, at either time in protein-to-DNA ratios between resected and transected animals. Mucosal sucrase activities expressed per unit length of smal1 intestine were increased in resected compared to transected rats at both 2 and 6 wk after surgery, although statistical

1990

Tabje

KWAN ET AL.

1.

GASTROENTEROLOGY Vol. 92, No. 6

Characteristics of Mucosal Tissue in Transected

and Resected

Rats 6 wk

2 wk Tissue parameter

Transected

Wet weight (mg/cm) Protein (mg/cm) Protein recovery (%)b DNA (mghm) Protein/DNA ratio Sucrase activity” Sucrase activity/lengthd Sucrase recovery (%)b Villus height (Pm)

Resected

Transected

57.6 + 11.1 5.9 * 0.4

96.1 ? 8.ga 10.8 2 0.7'

42.7 f 0.6

72.8 -+ 8.6’=

1.1 2 0.1 0.29 r 0.02

1.1 * 0.1 0.47 2 O.O1°

5.7 t 0.2 1.3 2 0.1 0.27 f 0.01

9.5 t 0.3O 1.0 k 0.1 0.39 k o.03a

20.5 k 0.2 73 * 18 1.3 + 0.3

22.7 ir 1.4 96 ? 12 3.4 f 0.7e

21.4 +r 0.6 80 k 11 1.5 k 0.3

26.6 * 1.9

Resected

75 * 10 2.5 k 0.3e

8.6 * 0.6

9.3 + 1.0 942 -c 19 320 f 10 1.7 ? 0.2

8.7 f 1045 k 444 * 2.7 ?

1.22 rr 0.20

1.37 * 0.08

Crypt height (Pm)

7.5 + 0.5 845 t 26 342 2 13

Mitotic indexg Vesicle volume (pl/mglh

1.8 2 0.2

1187 + 3lf 511 XL 16' 4.8 2 0.3f

1.38 2 0.15

1.44 t 0.20

1.2 2d 13f 0.2f

DNA, deoxyribonucleic acid. Values were expressed as mean 2 SE; n = 6 rats per transected group, and 11 rats per resected group. Op < 0.05, t-test versus transection control. b Percentage of protein or sucrase recovered in brush-border membrane vesicles compared to mucosal homogenate. ’ Micromoles of glucose per minute per milligram protein. d Micromoles of glucose per minute per milligram protein per centimeter. e p < 0.1, t-test versus transection control. f p < 0.005, t-test versus transection control. s Mitotic index, defined as number of mitotic figures per crypt section. h For vesicle volumes, the equilibrium values were determined after 90-100 min of incubation.

significante was not achieved (p < 0.10). These changes in mucosal weight, protein, DNA, and enzyme activities are similar to results observed previously (7,ll). Recovery of protein and sucrase activities in transected and resected animals were similar at 2 and 6 wk.

Morphometric

Parameters

Morphometric measurements are shown in Table 1. Significant increases in residual proximal smal1 intestinal villus and crypt heights as wel1 as mitotic indices (p < 0.005 for all) were observed in the resected animals at both 2 and 6 wk after surgery compared to transected control animals. The volume of the brush-border membrane vesicles can be estimated by comparing the counts per minute available in the incubation medium and the counts per minute retained by the vesicle after equilibration with glucose in the medium at a conTable

2. Summary

of Kinetics

of Sodium-Dependent

Glucose

centration of 0.8 PM for 90-100 min. By knowing the volume of the incubation medium and the amount of vesicle protein present, the average volume of the vesicles can be calculated and expressed as microliters per milligram of vesicle protein. This provides an estimate of membrane vesicle size and indirectly permits comparison of differing membrane vesicle preparations. Vesicle volumes from the two animal groups are shown in Table 1. There were no significant differences in the average apparent sizes of the vesicle preparations used in the experiments from either resected or transected animals.

Kinetics of Sodium-Dependent Uptake

Figures 1 and 2 show representative plots of sodium-dependent D-glucose uptake illustrated with initial uptake rate on the ordinate and uptake divided by glucose concentration on the abscissa Transport 6 wk

2 wk

Kinetic parameters Low-affinity system Km (til V,, (nmol * mg protein-’ . min-‘) n High-affinity system Km (til V,,, (nmol . mg protein-’ . min-‘) n

Transection

Resection

Transection

280.4 2 53.7a

177.5 2 45.10

271.7 2 17.5”

3.05 -1-0.32' 3

3.73 2 0.99"

4.69 + 0.23" 3

4

9.1 +- 1.30

6.2 +r 1.9”

0.17 + 0.010

0.12 C 0.06"

3

DGlucose

10.6 2 4.2’ 0.16 2 0.09" 3

4

K,,,, Michaelis constant; n, number of experiments. a At p < 0.05, no statistical systems at 2 or 6 wk for transected or resected rat groups.

differences

detected

Resection 267.8 ‘- 83.1’= 3.33 r+ 0.57O 4

6.5 & l.la 0.06 k 0.01" 4

for either the low- or high-affinity

MEMBRANE TRANSPORT AFTER BOWEL RESECTION

june 1987

(Woolf-Augustinsson-Hofstee plot). The Hofstee transformation of the data from the residual smal1 bowel of the resected rats and the proximal smal1 bowel of the transected rats demonstrated a clear curvilinear relationship consistent with multiple transport mechanisms. As in our previous studies with normal rats (161, two saturable systems were determined; one was a relatively low-affinity, highcapacity system and the other was a relatively highaffinity, low-capacity system. Table í! summarizes the kinetic constants obtained from different preparations for the two experimental groups with each preparation representing pooled vesicles from 2-3 rats. Results from four preparations aré shown for the resected animals and results from three preparations are shown for transected animals. At both 2 and 6 wk after massive distal smal1 bowel resection, the kinetic parameters of both

10

30

20 Glucose uptake

1991

i [9lucose]

3 B

F

10

30

20

Glucos? uptake

/ [ghtcca]

Figure 2. Representative Hofstee plots of brush-border membrane vesicle sodium-dependent o-glucose uptake in rats 6 wk after surgery. A. Transected (control) experiment. B. Resected experiment. Similar results are observed between transected and resected rats, as observed for the 2-wk rats.

Glucose uptake / [slucose]

n-glucose transport systems were not significantly different from those defined in the transection control rats (p < 0.05). Accordingly, these data would suggest that the functional assembly of the brushborder membrane is not altered after massive intestinal resection. An increase in the o-glucose transport observed with in vivo perfusion methods may be due to a greater absorptive surface, i.e., morphologie adaptation or unstirred layer effects, or both (26,271. u 40

Glucose uptake

Figure

/ [ghhxse]

1. Representative Hofstee plots of brush-border membrane vesicle sodium-dependent o-glucose uptake in rats 2 wk after surgery. A. Transected (control] experiment. B. Resected experiment. Curvilinear transformations were observed in each case, indicating the presence of more than one transport system. Two saturable systems were determined by Michaelis-Menten kinetics: a low-affinity, high-capacity system and a highaffinity, low-capacity system.

Discussion n-Glucose is a universal substrate; accordingly, it has been considered an excellent marker for assessing functional changes across the brush-border membrane. It is generally accepted that n-glucose uptake in the smal1 bowel requires sodium cotransport across the brush-border membrane (l3,14). Furthermore, previous studies have suggested the pres-

1992

GASTROENTEROLOGY Vol. 92, No. 6

KWAN ET AL.

ence of two or more sodium-dependent transport processes in the smal1 intestine (13,14). These can be defined by differences in kinetic parameters, sodium stoichiometries, and differential sensitivities to inhibition with phlorizin (15). Under the conditions in the present study, the high-affinity system has a K,,, generally below 50 PM and the low-affinity system possesses a K, in the order of 200-350 PM, differing at least several-fold from the high-affinity system (16-18).

The present results demonstrate that the residual mucosal tissue of the rat smal1 intestine exhibits a hyperplastic response defined structurally by tissue and by morphometric parameters after massive smal1 bowel resection. At 2 wk, the segmental protein ahd DNA content increased by about 80% and SO%, respectively, with little change in the protein-toDNA ratio compared to the transected controls. Crypt and villus heights increased by about 4O%, with a 2.4fold increase in the mitotic index. This hyperplastic response was also seen 6 wk after surgery. These results are consistent with previous studies (1,3,7) as wel1 as with the observations of Hanson et al. (28) indicating that a new steady state has been reached in the rat within 12 days of smal1 intestinal resection. As expected, the specific activity of sucrase was similar in the two groups, and if expressed per unit length of smal1 bowel, it was somewhat higher in the resected rats although this did not reach statistical significante. Despite the marked hyperplastic response in the residual smal1 intestine, there was no significant differente in the kinetic parameters of either the lowor high-affinity systems in the resected compared to transected control rats at 2 and 6 wk after intestinal resection. The K, for the high-affinity system ranged from 6 to 11 PM. For the low-affinity system it was 20- to 30-fold higher (ranging from 150 to 280 PM). The V,,, of the high-affinity system ranged from 0.06 to 0.17 nmol . mg protein-* . min-l; the V,,, of the low-affinity system was considerably higher (3 LM. 7 nmol . mg proteiñ* . min-‘). Although the V,, appeared to be elevated in the resected rats at 2 wk and higher in the transected rats at 6 wk, these differences were not significant. The kinetic data suggest that the hyperplastic response in proximal smal1 intestine after distal resection in the rat is accompanied by a persistente of the membrane functional characteristic for the two sodium-dependent Dglucose transport systems despite an altered pattern of enterocyte proliferation and maturation. Our results are consistent with the observations of Menge et al. (20) that described D-glucose uptake into ileal brush-border membrane vesicles examined 4 wk after proximal smal1 bowel resection. Kinetic

analysis of sodium-dependent n-glucose transport was not done in their study after resection, but the functional characteristics of the brush-border membranes after surgery appeared to be maintained as reflected in similar “overshoot” uptakes for Dglucose in the presence of a 100 mM NaSCN gradient identical to that used in the present study. Our results in resected rats concur with these earlier observations, but comparisons are made with transection rather than nonsurgical controls. In addition, findings after distal rather than proximal smal1 bowel resection are described and extended to the kinetic parameters of the two previously reported (18) o-glucose transport systems in the rat smal1 intestine. It is conceivable that changes in the o-glucose transport characteristics occur but were not detected by the techniques used in the present study or in the previous investigation by Menge et al. (20) after proximal smal1 bowel resection. Interpretation of kinetic data on n-glucose uptake in brush-border membrane vesicles may be subject to such considerations as heterogeneity of the membrane preparations used, as these were derived from cells at diff ering stages of enterocyte diff erentation. Morphologie and functional maturation of adapting enterocytes, for example, may become dissociated in the residual hyperplastic smal1 intestine after massive resection. In another study, Menge et al. (29) observed a shortening of the time needed for enterocytes to reach a stage of adequate differentation so that amino acid absorption could occur. Additional studies, possibly using autoradiographic methods (29,30), might further elucidate cellular membrane transport changes in adapting smal1 intestine after massive resection. In summary, the results using the present techniques suggest that an increase in substrate absorption occurs through an increase in intestinal transport area with persistente of the functional characteristics of sodium-dependent o-glucose transport assemblies.

References 1. Williamson

RCN. Intestinal adaptation. Structural, functional and cytokinetic changes. N Engi J Med 1978;298:1393400. 2. Williamson RCN. Intestinal adaptation. Mechanisms of control. N EnglJ Med 1978;298:1444-50. 3. Dowling RH, Booth CH. Structural and functional changes following smal1 intestinal resection in the rat. Clin Sci 1967;32:13949. 4. Hanson WR, Osborne

JW, Sharp JG. Compensation by the residual intestine after intestinal resection in the rat. Influence of amount of tissue removed. Gastroenterology 1977; 72:892-700.

5. Al-Mukhter

MYT, Polak JM, Bloom SR, Wright NA. The search for appropriate measurements of proliferative and morphological status in studies on intestinal adaptation. In:

I

June 1987

8.

7.

8.

9.

10.

ll.

12.

13.

14.

15.

16.

17.

Robinson JWL, Dowling RH, Riecken EO, eds. Mechanisms of intestinal adaptation. Boston: MTP Press, 19823-25. Urban E. Intestinal brush-border alkaline phosphatase in the rat after proximal smal1 bowel resection. Proc Sec Exp Bio1 Med 1977;155:99-104, McCarthy DM, Kim YS. Changes in sucrase, enterokinase and peptide hydrolase after intestinal resection. The association of cellular hyperplasia and adaptation. J Clin Invest 1973; 52:949-51. Gleeson MH, Dowling RH, Peters TJ. Biochemical change in intestinal mucosa after experimental smal1 bowel bypass in the cat. Clin Sci 1972;43:743-57. Menge H, Robinson JWL. The relationship between the functional and structural alterations in rat smal1 intestine following proximal resection of varying extent. Res Exp Med (Berl) 1978;173:41-53. Feldman EJ, Dowling RH, Peters TJ. Effect of oral vs. intravenous nutrition on the intestinal adaptation after smal1 bowel resection in the dog. Gastroenterology 1976;70:712-9. Garrido AB, Freeman HJ, Chung YC, Kim YS. Amino acid and peptide absorption after proximal smal1 intestinal resection in the rat. Gut 1979;20:114-20. Murer H, Kinne R. The use of isolated membrane vesicles to study epithelial transport processes. J Membr Bio1 1980; 55:81-95. Honegger P, Gershon E. Further evidente for the multiplicity of carriers for free glucalogues in hamster smal1 intestine. Biochim Biophys Acts 1974;352:127-34. Semenza G, Kessler M, Hosang M, Weber J, Schmidt U. Biochemistry of the Na+, n-glucose cotransport of the smallintestinal brush-border membrane. Biochim Biophys Acts 1984;779:343-79. Stevens BR, Kaunitz JD, Wright EM. Intestinal transport of amino acid and sugars: advances using membrane vesicles. Ann Rev Physiol 1984;46:417-33. Dorando FC, Crane RK. Studies of the kinetics of Na+ gradient-coupled transport as found in brush-border membrane vesicles from rabbit jejunum. Biochim Biophys Acts 1984;772:273-87. Kaunitz DJ, Wright EM. Kinetics of sodium o-glucose cotransport in bovine intestinal brush-border vesicles. J Membr Bio1 1984;79:41-51.

MEMBRANE TRANSPORT AFTER BOWEL RESECTION

1993

18. Freeman HJ, Quamme GA. Age-related changes in sodiumdependent glucose transport in rat smal1 intestine. Am J Physiol 1986;251:6208-17. 19. Hopfer IJ, Nelson K, Perrotto J, Isselbacher KJ. Glucose transport in isolated brush-border membrane from rat smal1 intestine. J Bio1 Chem 1973;248:25-32. 20. Menge H, Murer H, Robinson JWL. Glucose transport by brush-border membrane vesicles after proximal resection or ileo-jejunal transposition in the rat. J Physiol 1978;274:9-16. 21. Scudamore CH, Freeman HJ. Effects of smal1 bowel transection, resection or bypass in 1,2-dimethylhydrazine-induced rat intestinal neoplasia. Gastroenterology 1983;84:725-31. 22. Kessler M, Acute 0, Storella C, Murer H, Semenza G. A modified procedure for the rapid preparation of efficiently transporting vesicles from smal1 intestinal brush-border membranes. Their use in investigating some properties of n-glucose and choline transport system. Biochim Biophys Acts 1978;506:136-53. 23. Lowry OH, Rosebrough NJ, Farr AL, Randall RJ. Protein measurement with the Folin phenol reagent. J Bio1 Chem 1951;193:265-75, 24. Giles KW, Myers A. An improved diphenylamine method for the estimation of deoxyribonucleic acid. Nature 1965;206:93. 25. Dahlqvist A. Assay of intestinal disaccharidases. Anal Biochem 1968;22:99-107. 26. Thomson ABR, Dietschy JM. Experimental demonstration of the effect of the unstirred water layer on the kinetic constants of the membrane transport of u-glucose in rabbit jejunum. J Membr Bio1 1980;54:221-9. 27. Thomson ABR. Effect of two defined formula diets on jejunal and colonic uptake of hexoses in control and ileal resected rabbits. Clin Invest Med 1985;8:296-306. 28. Hanson WR, Osborne JW, Sharp JG. Compensation by the residual smal1 intestine after intestinal resection in the rat. 11. Influence of the postoperative time interval. Gastroenterology 1977;72:701-5. 29. Menge H, Sepulveda FV, Smith MW. Cellular adaptation of amino acid transport following intestinal resection in the rat. J Physiol 1983;334:213-23. 30. Smith MW. Expression of digestive and absorptive function in differentiating enterocytes. Ann Rev Physiol 1985;47: 247-60.