Primary structure of a 15-kDa protein from rat intestinal epithelium. Sequence similarity to fatty-acid-binding proteins

Initial studies of the cytoplasmic FABP superfamily

Our colleagues and we have determined the complete primary structure of a low molecular weight cytoplasmic FABP (also known as z-protein) that binds to LCFAs with high affinities, obtained from rat liver. At the same time, we were the first to propose that rat FABP1, bovine FABP8 (MP-2), bovine CRBP and rat CRABP constituted a protein superfamily in 1982. Since then, extensive investigation of structures, functions and expressions has been carried out on a whole family of FABPs. Analyses of rat heart FABP; FABP1, FABP3 and alpha(2U)-globulin expressed in rat kidney; discovery of ileal FABP6 (I-15P); and first application of FABP2 as a diagnostic marker also stand out in particular.

Spatio-temporal distribution of fatty acid-binding protein 6 (fabp6) gene transcripts in the developing and adult zebrafish (Danio rerio)

We have determined the structure of the fatty acid-binding protein 6 (fabp6) gene and the tissue-specific distribution of its transcripts in embryos, larvae and adult zebrafish (Danio rerio). Like most members of the vertebrate FABP multigene family, the zebrafish fabp6 gene contains four exons separated by three introns. The coding region of the gene and expressed sequence tags code for a polypeptide of 131 amino acids (14 kDa, pI 6.59). The putative zebrafish Fabp6 protein shared greatest sequence identity with human FABP6 (55.3%) compared to other orthologous mammalian FABPs and paralogous zebrafish Fabps. Phylogenetic analysis showed that the zebrafish Fabp6 formed a distinct clade with the mammalian FABP6s. The zebrafish fabp6 gene was assigned to linkage group (chromosome) 21 by radiation hybrid mapping. Conserved gene synteny was evident between the zebrafish fabp6 gene on chromosome 21 and the FABP6/Fabp6 genes on human chromosome 5, rat chromosome 10 and mouse chromosome 11. Zebrafish fabp6 transcripts were first detected in the distal region of the intestine of embryos at 72 h postfertilization. This spatial distribution remained constant to 7-day-old larvae, the last stage assayed during larval development. In adult zebrafish, fabp6 transcripts were detected by RT-PCR in RNA extracted from liver, heart, intestine, ovary and kidney (most likely adrenal tissue), but not in RNA from skin, brain, gill, eye or muscle. In situ hybridization of a fabp6 riboprobe to adult zebrafish sections revealed intense hybridization signals in the adrenal homolog of the kidney and the distal region of the intestine, and to a lesser extent in ovary and liver, a transcript distribution that is similar, but not identical, to that seen for the mammalian FABP6/Fabp6 gene.

Establishment and characterization of monoclonal and polyclonal antibodies against human intestinal fatty acid-binding protein (I-FABP) using synthetic regional peptides and recombinant I-FABP

We have succeeded in raising highly specific anti-human intestinal fatty acid-binding protein (I-FABP) monoclonal antibodies by immunizing animals with three synthetic regional peptides, i.e., the amino terminal (RP-1: N-acetylated 1-19-cysteine), middle portion (RP-2: cysteinyl-91-107) and carboxylic terminal (RP-3: cysteinyl-121-131) regions of human I-FABP, and the whole I-FABP molecule as antigens. We also raised a polyclonal antibody by immunizing with a recombinant (r) I-FABP. To ascertain the specificity of these antibodies for human I-FABP, the immunological reactivity of each was examined by a binding assay using rI-FABP, partially purified native I-FABP and related proteins such as liver-type (L)-FABP, heart-type (H)-FABP, as well as the regional peptides as reactants, and by Western blot analysis. In addition, the expression and distribution of I-FABP in the human gastrointestinal tract were investigated by an immunohistochemical technique using a carboxylic terminal region-specific monoclonal antibody, 8F9, and a polyclonal antibody, DN-R2. Our results indicated that both the monoclonal and polyclonal antibodies established in this study were highly specific for I-FABP, but not for L-FABP and H-FABP. Especially, the monoclonal antibodies raised against the regional peptides, showed regional specificity for the I-FABP molecule. Immunoreactivity of I-FABP was demonstrated in the mucosal epithelium of the jejunum and ileum by immunohistochemical staining, and the immunoreactivity was based on the presence of the whole I-FABP molecule but not the presence of any precursors or degradation products containing a carboxylic terminal fragment. It is concluded that some of these monoclonal and polyclonal antibodies, such as 8F9, 4205, and DN-R2, will be suitable for use in research on the immunochemistry and clinical chemistry of I-FABP because those antibodies can recognize both types of native and denatured I-FABP. In order to detect I-FABP in blood samples, it is essential to use this type of antibody, reactive to native type of I-FABP. It is anticipated that, in the near future, such a method for measuring I-FABP will be developed as a useful tool for diagnosing intestinal ischemia by using some of these antibodies.

Studies of the FABP family: a retrospective

Following my research on the role played by soluble proteins in their function as hydrophobic ligand carriers acting through squalene epoxidase, Dr Odani and I started to work together on low molecular lipid binding proteins. As a result of this collaboration, in 1982 we managed to determine the complete primary structure of Z-protein in rat liver. This was the first report ever to give the complete amino acid sequence of a fatty acid binding protein (FABP). This gave momentum to further such research, and now extensive exploration has been carried out on a whole family of homologous intracellular hydrophobic ligand binding proteins, the product of the expression of an ancient gene family in numerous organisms. Takahashi et al. have determined the primary structures of mammalian FABP family protein in liver, intestine, heart, kidney, and skin through amino acid sequencing as well as through determination of the cDNA sequence. Out of all my research on the FABP family, I believe, my initial study on FABP in liver, my work on kidney FABP, heart type FABP and my discovery of an I-15P (BAPB) and I-FABP application as a diagnostic marker stand out in particular.

The relative ligand binding preference of the murine ileal lipid binding protein

The ileal lipid binding protein (ILBP), a member of the intracellular lipid binding protein family, is a 14-kDa protein that has bile and fatty acids as possible physiological ligands. The ligand binding specificity of this protein is not well characterized. Therefore, we studied the lipid binding activity of purified recombinant murine ILBP (mILBP) in vitro. These studies demonstrated by direct analysis the interaction of mILBP with naturally occurring bile and fatty acids. The rank order of binding preference for fatty acids, or unconjugated and conjugated bile acids, was assessed. Among fatty acids, mILBP preferred species that had longer chain length and increased saturation, similar to other members of the intracellular lipid binding protein family. Among the bile acids, mILBP showed the greatest preference for conjugated species that contained a doubly hydroxylated steroid moiety. The results demonstrate that mILBP exhibits a preference for certain species of bile and fatty acids.

The fatty acid transport function of fatty acid-binding proteins

The intracellular fatty acid-binding proteins (FABPs) comprise a family of 14-15 kDa proteins which bind long-chain fatty acids. A role for FABPs in fatty acid transport has been hypothesized for several decades, and the accumulated indirect and correlative evidence is largely supportive of this proposed function. In recent years, a number of experimental approaches which more directly examine the transport function of FABPs have been taken. These include molecular level in vitro modeling of fatty acid transfer mechanisms, whole cell studies of fatty acid uptake and intracellular transfer following genetic manipulation of FABP type and amount, and an examination of cells and tissues from animals engineered to lack expression of specific FABPs. Collectively, data from these studies have provided strong support for defining the FABPs as fatty acid transport proteins. Further studies are necessary to elucidate the fundamental mechanisms by which cellular fatty acid trafficking is modulated by the FABPs.

Fatty acid binding protein isoforms: structure and function

Although structural aspects of cytosolic fatty acid binding proteins (FABPs) in mammalian tissues are now well understood, significant advances regarding the physiological function(s) of these proteins have been slow in forthcoming. Part of the difficulty lies in the complexity of the multigene FABP family with nearly twenty identified members. Furthermore, isoelectric focusing and ion exchange chromatography operationally resolve many of the mammalian native FABPs into putative isoforms. However, a more classical biochemical definition of an isoform, i.e. proteins differing by a single amino acid, suggests that the operational definition is too broad. Because at least one putative heart H-FABP isoform, the mammary derived growth inhibitor, was an artifact (Specht et al. (1996) J. Biol. Chem. 271: 1943-49), the ensuing skepticism and confusion cast doubt on the existence of FABP isoforms in general. Yet, increasing data suggest that several FABPs, e.g. human intestinal I-FABP, bovine and mouse heart H-FABP, rabbit myelin P2 protein and bovine liver L-FABP may exist as true isoforms. In contrast, the rat liver L-FABP putative isoforms may actually be due either to bound ligand, post-translational S-thiolation and/or structural conformers. In any case, almost nothing is known regarding possible functions of either the true or putative isoforms in vitro or in vivo. The objective of this article is to critically evaluate which FABPs form biochemically defined or true isoforms versus FABPs that form additional forms, operationally defined as isoforms. In addition, recent developments in the molecular basis for FABP true isoform formation, the processes leading to additional operationally defined putative isoforms and insights into potential function(s) of this unusual aspect of FABP heterogeneity will be examined.

Regulation of expression of human intestinal bile acid-binding protein in Caco-2 cells

Molecular mechanisms of the bile acid active transport system in the ileal enterocytes remain unknown. We examined whether bile acids affect human enterocyte gene expression of intestinal bile acid-binding protein (I-BABP), a component of this transport system. Differentiated Caco-2 cells were incubated in the presence of human bile, bile acids or other lipids. The level of I-BABP expression was evaluated by Northern and Western blot analyses. A 24 h incubation of Caco-2 cells in a medium containing either bile or bile acids resulted in a remarkable 7.5-fold increase in the I-BABP mRNA level over the control level. Neither cholesterol, palmitic acid, phosphatidylcholine nor cholestyramine treated bile showed any difference in I-BABP mRNA expression from the control. Bile acid treatment increased the level of I-BABP mRNA in Caco-2 cells in a time- and dose-dependent manner. Western blot analysis showed that this induction led to increase in cytosolic I-BABP. Chenodeoxycholic acid and deoxycholic acid showed greater induction effects than other hydrophilic bile acids, including their own glycine conjugates. Pretreatment by actinomycin D or cycloheximide completely inhibited the up-regulation of I-BABP expression by bile acid. Bile acids, especially lipophilic bile acids, increase the I-BABP expression in Caco-2-cells, suggesting that luminal bile acids play an important role in regulating the I-BABP gene expression.

Time-resolved fluorescence of intestinal and liver fatty acid binding proteins: role of fatty acyl CoA and fatty acid

The effect of fatty acyl CoA and fatty acid on the solution structure and dynamics of two intestinal enterocyte fatty acid binding proteins, intestinal (I-FABP) and liver (L-FABP), was examined by time-resolved fluorescence of FABP aromatic amino acid residues. I-FABP Trp displayed two rotational correlation times, 6.6 and 0.4 ns. reflecting motion of the protein as a whole and segmental mobility of Trp. Neither oleoyl CoA, oleic acid, nor CoASH altered overall I-FABP rotational correlation time. However, oleic acid and CoASH increased I-FABP Trp segmental mobility, while oleoyl CoA and CoASH decreased I-FABP Trp limiting anisotropy (order). The angle of I-FABP Trp "wobbling in a cone" was increased by ligands in the order oleoyl CoA > CoASH > oleic acid. L-FABP Trp segmental mobility. L-FABP overall rotational motion, in contrast to that of I-FABP, was significantly increased by ligands in the order oleoyl CoA > oleic acid > CoASH. cis-Parinaric acid and cis-parinaroyl CoA bound to L-FABP also reflected overall L-FABP motion but yielded longer rotational correlation times, 8.2 and 10.7 ns, than the respective apo-FABPs. Such effects were not observed with I-FABP. Finally, both cis-parinaric acid and cis-parinaroyl CoA were much less ordered in the I-FABP ligand binding site than with L-FABP. These observations suggest that the rotational dynamics of L-FABP and its conformation are more sensitive to ligands than I-FABP. Further, ligands such as fatty acids, fatty acyl CoAs, and/or CoASH differentially modulate the I-FABP and L-FABP dynamics, and the ligand binding sites of these proteins differ in their ability to order the ligands.

Intracellular lipid-binding proteins and their genes

Intracellular lipid-binding proteins are a family of low-molecular-weight single-chain polypeptides that form 1:1 complexes with fatty acids, retinoids, or other hydrophobic ligands. These proteins are products of a large multigene family of unlinked loci distributed throughout the genome. Each lipid-binding protein exhibits a distinctive pattern of tissue distribution. Transcriptional control, regulated by a combination of peroxisome proliferator activated receptors and CCAAT/enhancer-binding proteins, allows for a variety of both cell and tissue-specific expression patterns. In some cells, fatty acids increase the expression of the lipid-binding protein genes. Fatty acids, or their metabolites, are activators of the peroxisome proliferator-activated receptor family of transcription factors. Therefore, as the concentration of lipid in the diet increases, the expression of lipid-binding proteins coordinately increases. As revealed by X-ray crystallography, the lipid-binding proteins fold into beta-barrels, forming a large internal water-filled cavity. Fatty acid ligands are bound within the cavity, occupying only about one-third of the accessible volume. The bound fatty acid is stabilized via a combination of enthalpic and entropic forces that govern ligand affinity and selectivity. Cytoplasmic lipid-binding proteins are the intracellular receptors for hydrophobic ligands, delivering them to the appropriate site for use as metabolic fuels and regulatory agents.

Ontogenic and glucocorticoid-accelerated expression of rat 14 kDa bile acid-binding protein

BACKGROUND

A 14 kDa protein is a major rat ileal cytosolic bile acid-binding protein (14 kDa I-BABP). This report describes the normal and glucocorticoid-accelerated postnatal expression of 14 kDa I-BABP. METHODS. 14 kDa I-BABP and its mRNA were detected by antiserum and antisense cRNA probe, respectively, in ileum and ovary from 7-, 14-, 21-, 28-, and 35-day-old rats.

RESULTS

A positive histochemical reaction with 14 kDa I-BABP antiserum was found in cytosol of ileal enterocytes and ovarian luteal cells at 21 and 35 days of age, respectively. Likewise, Northern blot analysis indicated that the cRNA probe hybridized to a single transcript of 500 bp in total cellular RNA prepared from the ileum of 21-day-old and ovary of 35-day-old rats. Corticosteroid treatment resulted in a histochemical reaction in ileum of 14-day-old animals as compared to the appearance of this reaction in 21-day-old control littermates. Similarly, Northern blot analysis detected the earlier appearance of mRNA levels in corticosteroid-treated animals (11 days vs. 17 days in control animals).

CONCLUSIONS

14 kDa I-BABP and its mRNA are normally expressed in rat ileum at 17 days of postnatal life. 14 kDa I-BABP is expressed considerably later in rat ovary. Corticosteroid treatment results in precocious expression of ileal 14 kDa I-BABP.

Effect of bile on the intestinal bile-acid binding protein (I-BABP) expression. In vitro and in vivo studies

Enterocytes actively transport bile acids from the ileal lumen to the portal blood. This physiological process greatly contributes to maintaining the bile acid homeostasis. However, little is known about the molecular mechanisms involved in this transport system. The effect of bile on gene expression of the intestinal bile-acid binding protein (I-BABP) expressed in the enterocytes was studied in vivo, using the by-pass method, and in vitro, using organ culture of ileum explants and Caco-2 cell line. The low cytosolic I-BABP concentration and I-BABP mRNA level found in diverted ileum was totally recovered when bile was added in the ileal lumen. Northern blot analysis of the ileal explants revealed a dose-dependent increase in the I-BABP mRNA in the presence of bile. In Caco-2 cells, the I-BABP transcript was dramatically increased in the presence of human bile while it was undetectable in the control cultures. These data offer the first evidence that biliary components regulate the I-BABP gene expressed in the enterocytes.

Tissue-specific regulation of the expression of rat intestinal bile acid-binding protein

A lipid-binding protein identical to the rat intestinal bile acid-binding protein, termed I-15P, was expressed in steroid hormone-producing tissues such as ovary and adrenal gland, but not testis. In immature rats, I-15P was expressed in intestine but not in ovaries. The expression of I-15P in the ovaries of immature rats was induced to the level in immature rats by gonadotropin treatment. This suggests that the expression of I-15P in the ovaries is controlled by the ovarian cycle. The present results indicate that the expression of I-15P is developmentally and hormonally controlled in a tissue-specific manner.

Molecular cloning, expression, and characterization of a human intestinal 15-kDa protein

We have isolated a cDNA encoding a human intestinal 15-kDa protein (I-15P) from a human ileal lambda gt 11 cDNA library, using a full-length rat I-15P cDNA. One clone encompassed 571 nucleotides and encoded a 128-amino-acid protein with a calculated molecular mass of 14355 Da. The deduced amino acid sequence of human I-15P showed high similarity to the rat counterpart (78%), mouse ileal lipid-binding protein (80%) and porcine gastrotropin (75%). It also exhibited 36% similarity to human liver fatty-acid-binding protein (L-FABP). Northern blot analysis of human I-15P revealed a single transcript only in ileum, however, the reverse-transcription/PCR demonstrated expression in ovary and placenta, but it was much lower than in ileum. Transformation of Escherichia coli with the I-15P cDNA resulted in the efficient expression of a protein that was identical to the ileal cytosolic I-15P. In vitro binding studies revealed that the bacterially expressed recombinant I-15P showed much lower affinities for palmitate and oleate than L-FABP. However, it showed similar affinity for taurocholate, compared with a control, BSA. Comparison of the structural features of human I-15P and human L-FABP suggested that loss of a long alpha-helix region and hydrophobic profile of I-15P may be attributable to a unique ligand-binding specificity of I-15P.

Isolation of a novel collagen-binding protein from the mushroom, Hypsizigus marmoreus, which inhibits the Lewis lung carcinoma cell adhesion to type IV collagen

A type IV collagen-binding protein of 23 kDa was isolated from the mushroom, Hypsizigus marmoreus. This protein, HM 23, bound to type IV and type I collagens and gelatin, and to much lesser extent to fibronectin, but not to laminin or bovine serum albumin. The adhesion of Lewis lung carcinoma cells was inhibited when the type IV collagen substratum was pretreated with HM 23. A computer search of the determined partial amino acid sequence indicated no homologous proteins reported. These results indicate that HM 23 is a hitherto undescribed fungus protein that can interact with animal extracellular matrix proteins.

The mouse ileal lipid-binding protein gene: a model for studying axial patterning during gut morphogenesis

Normal, chimeric-transgenic, and transgenic mice have been used to study the axial patterns of ileal lipid-binding protein gene (Ilbp) expression during and after completion of gut morphogenesis. Ilbp is initially activated in enterocytes in bidirectional wave that expands proximally in the ileum and distally to the colon during late gestation and the first postnatal week. This activation occurs at the same time that a wave of cytodifferentiation of the gut endoderm is completing its unidirectional journey from duodenum to colon. The subsequent contraction of Ilbp's expression domain, followed by its reexpansion from the distal to proximal ileum, coincides with a critical period in gut morphogenesis (postnatal days 7-28) when its proliferative units (crypts) form, establish their final stem cell hierarchy, and then multiply through fission. The wave of reactivation is characterized by changing patterns of Ilbp expression: (a) at the proximal most boundary of the wave, villi contain a mixed population of scattered ileal lipid-binding protein (ILBP)-positive and ILBP-negative enterocytes derived from the same monoclonal crypt; (b) somewhat more distally, villi contain vertical coherent stripes of wholly ILBP-positive enterocytes derived from monoclonal crypts and adjacent, wholly ILBP-negative stripes of enterocytes emanating from other monoclonal crypts; and (c) more distally, all the enterocytes on a villus support Ilbp expression. Functional mapping studies of Ilbp's promoter in transgenic mice indicate that nucleotides -145 to +48 contain cis-acting elements sufficient to produce an appropriately directed distal-to-proximal wave of Ilbp activation in the ileum, to maintain an appropriate axial distribution of monophenotypic wholly reporter-positive villi in the distal portion of the ileum, as well as striped and speckled villi in the proximal portion of its expression domain, and to correctly support reporter production in villus-associated ileal enterocytes. Nucleotides -417 to -146 of Ilbp contain a "temporal" suppressor that delays initial ileal activation of the gene until the second postnatal week. Nucleotides -913 to -418 contain a temporal suppressor that further delays initial activation of the gene until the third to fourth postnatal week, a spatial suppressor that prohibits gene expression in the proximal quarter of the ileum and in the proximal colon, and a cell lineage suppressor that prohibits expression in goblet cells during the first two postnatal weeks.

Molecular cloning, tissue distribution, and expression of a 14-kDa bile acid-binding protein from rat ileal cytosol

A cDNA clone encoding the major intestinal cytosolic 14-kDa bile acid-binding protein (14-kDa I-BABP) was isolated from a rat ileal lambda gt22A library following immunoscreening using a monospecific antiserum raised against a 14-kDa polypeptide found in the rat ileal cytosol. One clone of 516 bp encoded a 128-amino acid protein with a predicted molecular mass of 14,544 Da. The deduced amino acid sequence of 14-kDa I-BABP showed 100% homology to rat intestinal 15-kDa protein (I-15P) and 72% homology to porcine 15-kDa gastrotropin, whereas comparison of I-BABP to rat 14-kDa fatty acid-binding proteins of liver, intestine, and heart revealed homologies of 44%, 25%, and 28%, respectively. Northern blot analysis revealed a single transcript of approximately 0.5 kb in ileum and ovary; however, the abundance of I-BABP mRNA was much greater in ileum than in ovary. No transcript was seen in RNA extracted from stomach, jejunum, colon, liver, adrenal, brain, heart, kidney, or testis. Transfection of the I-BABP cDNA into COS-7 cells resulted in the expression of a 14-kDa protein that was identical to the ileal cytosolic I-BABP as determined by immunoblotting. Photoaffinity labeling of expressed 14-kDa protein was saturable with respect to increasing concentrations of 7,7-azo[3H]taurocholate (Km, 83.3 microM; Vmax, 6.7 pmol/mg per 5 min). Taurocholate inhibited 7,7-azotaurocholate labeling by > 96% with lesser inhibition by taurochenodeoxycholate (83.1%), chenodeoxycholate (74.6%), cholate (50.5%), and progesterone (38.5%), whereas oleic acid and estradiol did not inhibit binding.

Expression and localization of intestinal 15 kDa protein in the rat

Rat intestinal 15 kDa protein (I-15P) is highly homologous to porcine gastrotropin. We studied the occurrence, distribution and subcellular localization of I-15P in the entire rat body, using the immunocytochemistry to localize protein and in situ hybridization to localize mRNA. Both techniques demonstrated the expression of I-15P in the enterocytes of ileum, luteal cells of ovary and a subpopulation of steroid-endocrine cells of adrenal gland. Immuno-electron microscopy further demonstrated that I-15P is localized in both the cytoplasmic and nuclear matrix regions of these cells. The present results suggest roles of I-15P not only in the transport of bile salts but also in the metabolisms of certain steroid hormones.

Immunocytochemical localization of rat intestinal 15 kDa protein, a member of cytoplasmic fatty acid-binding proteins

Rat intestinal 15 kDa protein (I-15P) is a member of the family of cytoplasmic fatty acid-binding proteins. Using a specific antiserum against I-15P, we studied the tissue distribution and subcellular localization of this protein in the entire rat body. By immunoblot analysis of cytosolic proteins, I-15P was detected not only in the distal portion of small intestine but also in the ovary and adrenal gland. Immunohistochemically, I-15P was localized to the absorptive epithelial cells as well as a subpopulation of enterochromaffin cells in the intestine, the lutein cells in the ovary, and subpopulations of cortical cells in the adrenal gland. Furthermore, I-15P-like immunoreactivity was also demonstrated in the surface mucous cells of stomach and the granular convoluted tubule cells of submandibular gland. Immuno-electron microscopy showed that the immunoreactivity was confined to the cytoplasmic matrix region, except in the enterochromaffin cells and granular convoluted tubule cells, where it was localized in the secretory granules. The present findings suggest that I-15P plays a role in the cellular metabolism of steroids.

Intestinal fatty acid-binding protein as a sensitive marker of intestinal ischemia

Determination of the serum level of intestinal fatty acid-binding protein has been used to detect rat intestinal ischemia following ligation or 30-min occlusion of the superior mesenteric artery. The normal values were under the minimal detectable level of less than 2 ng/ml in all the 10 rats. The serum fatty acid-binding protein level increased rapidly, to 340.7 +/- 54.6, 438.5 +/- 40.1, 388.1 +/- 37.4, and 292.2 +/- 95.7 ng/ml (P less than 0.01) at 1, 2, 4, and 8 hr after ligation, respectively. It also increased, to 347.2 +/- 127.7 ng/ml (P less than 0.01) at 1 hr, after a 30-min transient occlusion and then returned to a normal level. Histological studies showed destruction of the villi, disappearance of the mucosa, and transmural necrosis with the progress of time after ligation, while no remarkable morphological change was observed following 30-min transient occlusion. These observations strongly suggest that the intestinal fatty acid-binding protein is a useful biochemical marker for intestinal ischemia, particularly in the early reversible phase.