Intestinal Alkaline Phosphatase Activity Research Articles

Phytase activity in the human and rat small intestine.

Phytate is the major storage form of phosphorus in seeds and so is a common dietary constituent. Excessive ingestion of undegraded phytates can cause mineral deficiencies in humans. In addition, phytic acid is antineoplastic in animal models of both colon and breast carcinoma. There have been no previous studies quantifying phytase activity in the human small intestine although it is present in animals. Small intestinal phytase and alkaline phosphatase activity and distribution was measured in vitro in mucosal homogenates from two human small intestinal specimens obtained from transplant donors. Rat intestine was also studied for comparison. Phytase activity was found in human small intestine at low values (30 times less than that in rat tissue and 1000-fold lower than alkaline phosphatase in the same tissue). The activity was greatest in the duodenum and lowest in the ileum. In conclusion, the normal human small intestine has very limited ability to digest undegraded phytates. Although this may have adverse nutritional consequences with respect to metabolic cation imbalances, the presence of undigested phytate in the colon may protect against the development of colonic carcinoma.

Development and hormonal modulation of postnatal expression of intestinal alkaline phosphatase mRNA species and their encoded isoenzymes

In the rat, intestinal alkaline phosphatase (IAP) activity in the duodenum, but not jejunum, increases on day 22-24 after birth and exhibits higher activity hydrolysing phenyl phosphate (PhP) than beta-glycerophosphate (beta GP) [Moog and Yeh (1973) Comp. Biochem. Physiol. 44B, 657-666]. The mechanism underlying these developmental changes remains unknown. To define possible mechanisms, we have measured IAP activity and mRNA levels, and analysed IAP mRNA species and isoenzymes on postnatal days 12, 18, 24 and 32. Duodenal IAP activity and mRNA content were identical on postnatal days 12 and 18, but were 7-fold and 3-fold higher on day 24, respectively than on day 18. The increased IAP activity exhibited a high PhP/beta GP ratio and was accompanied by initial appearance of the 3.0 kb mRNA and 90 kDa isoenzyme. On day 32, duodenal IAP activity did not increase over the levels on day 24, whereas mRNA levels doubled. The lack of enzyme increase might be related in part to increased apical release, as luminal IAP activity increased from 2% of total mucosal IAP on days 12 and 18 to 7% and 14% on days 24 and 32 respectively. In the jejunum, IAP activity decreased postnatally, but mRNA content was unaltered; only the 2.7 kb mRNA and 65 kDa IAP isoenzyme were present. Administration of cortisone or cortisone+thyroxine induced simultaneous appearance of the duodenal 3.0 kb mRNA and 90 kDa isoenzyme with an increased PhP/beta GP ratio. Thus postnatal increase in duodenal IAP activity is related to the expression of a 90 kDa PhP-preferring isoenzyme encoded by the 3.0 kb mRNA. The low-PhP/beta GP-ratio 65 kDa isoenzyme is expressed in the duodenum and in the jejunum and is encoded by the 2.7 kb mRNA.

Secretion and distribution of rat intestinal surfactant-like particles after fat feeding.

Triacylglycerol feeding increases serum intestinal alkaline phosphatase (IAP) activity and leads to the appearance of an alkaline phosphatase-containing particle in the luminal washings over the apical surface of the rat enterocyte and in the blood (J. Clin. Invest. 84: 1355-1361, 1989). To examine the coordinate appearance of these particles and the enzyme and to follow their distribution in vivo after feeding, an enzyme-linked immunoabsorbent assay (ELISA) was developed, using antisera raised against the purified intact surfactant-like particle. Tissue compartments that were examined for phosphatase activity and particle content included isolated enterocytes, lamina propria, intestinal luminal washings, and serum. Alkaline phosphatase activity peaked earliest in the lamina propria (3 h), followed by the enterocyte and the luminal washings (5 h) and serum (7 h). Surfactant-like particle content peaked in the enterocyte and lamina propria at 3 h, followed by the serum (3-5 h) and the luminal washings (5 h). The buoyant density of the particle in the enterocyte (d = 1.08-1.09) and serum (d = 1.07-1.08) after fat feeding was similar to that of the isolated particle (d = 1.07-1.08). The density of particle proteins detected by ELISA in fasted serum was more diffuse and > 1.10, consistent with partial degradation of the particle and/or its proteins. These data confirm that the particle and its bound IAP are secreted from the enterocyte after triacylglycerol feeding and that they appear in compartments adjacent to both the basolateral (serum) and apical (luminal wash) surfaces of the enterocyte.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary fibers: their effects on intestinal digestive enzyme activities

Three plant foods (cabbage, guava, and mucilaginous isabgol husk) were fed to rats as the source of dietary fiber to study their effect on the activities of small intestinal disaccharidases (sucrase, maltase, and lactase) and alkaline phosphatase. Inclusion of cabbage and guava (at 5 and 10 g/100 g level) and isabgol (1 and 2 g/100 g) in the diets adversely affected the activities of sucrase, maltase, and alkaline phosphatase, which further decreased significantly ( P < 0.05) with an increase in level of dietary fiber from cabbage and guava. (J. Nutr. Biochem. 5:176–180, 1994.)

Human intestinal alkaline phosphatase—release to the blood is linked to lipid absorption, but removal from the blood is not linked to lipoprotein clearance

To evaluate a possible quantitative relationship between the rise in intestinal alkaline phosphatase (IAP) activity and triglyceride-rich lipoproteins in the blood after an oral fat intake, a specific and sensitive immunocatalytic assay was used. First, day to day variation of the basal IAP activity in the blood of eight volunteers was evaluated. One group of subjects with high basal IAP activity and great variations from one day to the other was distinguished from a group with low basal IAP activity and small day to day variations. The subjects with high basal IAP activities were all secretors of red blood cell antigens, while those with low basal IAP activities were non-secretors. The IAP activity in the blood rose after fat rich meals but not after fat free meals. To further investigate this, IAP activities were measured in the blood of 28 men before 3, 6, 9 and 12 h after a standardized oral fat load of a mixed meal type. The activity rose in all individuals and showed a similar time course as the rise in plasma TG concentration. The elevations of the IAP activity were, however, not quantitatively correlated with the elevations in TG concentration, nor were there any relations in time to peak levels. Subjects with high basal IAP increased their IAP activity more than those with low basal IAP, but within neither group there was any correlation between the basal IAP activity and the rise in IAP activity. IAP did not float with lipoproteins on ultracentrifugation of plasma, nor did IAP bind to lipid droplets from a fat emulsion added to plasma.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium phosphate

In an effort to reduce the risk of colorectal cancer development, oral calcium carbonate supplementation has been used in previous studies for the precipitation of cytotoxic bile acids and fatty acids. In human intervention trials its effect on mucosal hyperproliferation in the colorectum has not always been satisfactory. Because the complexation of calcium and bile acids requires the formation of calcium phosphate, we performed an intervention study in 14 healthy volunteers, giving them 1,500 mg calcium as Ca3(PO4)2 for 1 week. The effects of tricalcium phosphate on luminal and faecal parameters of cytolytic activity were evaluated before, during, and after calcium phosphate supplementation. The cytolytic activity of faecal water and intestinal alkaline phosphatase activity in faecal water were not affected by supplemental calcium phosphate. In duodenal bile, the proportion of cholic acid tended to increase, whereas that of chenodeoxycholic acid tended to decrease during calcium phosphate supplementation. Neither concentrations of total and individual faecal bile acids, nor that of faecal fat were affected during calcium phosphate supplementation. It is suggested that, although phosphate is involved in bile acid precipitation, phosphate competes for calcium in the binding of fatty acids. This might possibly explain the unchanged cytolytic potency of faecal water, and therefore does not make tricalcium phosphate a suitable calcium compound for dietary intervention.

Intestinal 5′Deiodinase Activity of Developing and Adult Chickens Selected for High and Low Body Weight

Intestinal 5′deiodinase activity (5′D) in adults from lines of chickens selected for high (HW) and low (LW) juvenile body weight was studied in vitro using reverse T 3 substrate. This avian intestinal 5′D activity is similar in its biochemical characteristics to the hepatic 5′D activity of mammals and birds. Adult 5′D activity was higher in line HW than LW; a pattern opposite to that prior to hatching. Previous studies have shown that thyroid hormones are important in triggering differentiation of the intestine during the latter part of embryonic life. Our studies indicate that the intestinal tissue is capable of producing T 3 that may be important in stimulating differentiation of the intestine itself, in preparation for posthatching food assimilation. The intestines of LW embryos, which hatch earlier than HW embryos, show both more rapid maturation, as indicated by intestinal alkaline phosphatase activity (a marker of differentiation), and higher 5′D activity. Increases in intestinal 5′D in the HW line at hatch may be important in the differential intestinal growth that leads to higher relative intestinal weights in HW than LW chicks after hatch. The magnitude of 5′D activity and the relative size of the intestine suggest that this organ could be an important contributor to plasma T 3.

The effect of bezafibrate treatment on serum alkaline phosphatase isoenzyme activities

A reduction in serum total alkaline phosphatase (ALP) activity is a well-documented side effect of treatment with bezafibrate and other fibric acid derivatives. To evaluate the effect of bezafibrate treatment on individual ALP isoenzyme activities, 10 patients were studied on two separate occasions, first, after a 6-week period on no drug treatment, and second, after 6 weeks of bezafibrate therapy. On each occasion, serum total ALP and ALP isoenzyme activities and serum γ-glutamyltransferase (GGT) activity were measured both after fasting and following the ingestion of a standardized high-fat meal rich in long-chain fatty acid triglycerides, as intestinal ALP activity is known to be influenced by dietary fat intake. Plasma aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were measured on fasting samples. In the fasting state, bezafibrate treatment resulted in a 25% reduction ( P < .01) in serum total ALP activity; liver ALP activity was reduced by 40% ( P < .01), and biliary ALP activity was reduced in those patients in whom it was initially detectable, while bone and intestinal ALP activities were unchanged. There was also a 15% reduction ( P < .05) in serum GGT activity, but no change in plasma AST or ALT activities. Serum intestinal ALP activity increased significantly ( P < .01) by 1 hour following ingestion of the high-fat meal, but treatment with bezafibrate did not change the magnitude of this response. There was no change in the activity of any other ALP isoenzyme following fat ingestion. This study demonstrates that the effect of bezafibrate on serum ALP activity is confined to the liver and biliary isoenzymes. Bezafibrate treatment also reduces serum GGT activity, which, like liver and biliary ALP activity, is increased during hepatic cholestasis. The pattern of enzyme changes observed provides information about a possible mechanism for the effect of bezafibrate and other fibric acid derivatives on serum ALP activity.

Effect of Estrogen in Relation to Dietary Vitamin D 3 and Calcium on Activity of Intestinal Alkaline Phosphatase and Ca-ATPase in Immature Chicks

The interaction between 17β-estradiol (E 2), vitamin D 3 (D 3), and dietary Ca on the activities of Ca-ATPase and alkaline phosphatase (AP) was determined in the intestine of young female chicks. Chicks ( n = 36) were assigned to two groups, one of which was transferred to a low Ca (0.2%) diet and the other maintained on a regular diet. One week later, each group was further divided into three subgroups and given daily injections of 0(oil), 0.25, or 0.5 mg E 2/kg body wt for 14 days. E 2 treatment as well as low dietary Ca significantly increased AP activity ( P < 0.05), whereas the highest E 2 dose decreased jejunal Ca-ATPase ( P < 0.05). In a separate study, day-old chicks ( n = 40) fed a purified diet supplemented with or without D 3 for 24 days were divided into two subgroups and administered daily injections of either 0 or 0.25 mg estrogen 3-benzoate/kg body wt for 5 days. E 2 alone or in combination with D 3 failed to change Ca-ATPase activity in either the duodenum or the jejunum. However, E 2 enhanced the D 3-stimulated AP activity measured in the supernatant of duodenum (D 3, P < 0.001; E 2, P > 0.05; E 2 × D 3, P < 0.05) and jejunum (D 3, P < 0.001; E 2, P > 0.05; E 2 × D 3, P = 0.06). Daily injections of 0.5 mg E 2/kg body wt for 6 days to 6-week-old D 3-adequate chicks ( n = 16) significantly increased AP activity in jejunum but not in liver and kidney ( P < 0.05). In conclusion, E 2 treatment enhanced the activity of intestinal AP but not Ca-ATPase. This enhancement was independent of dietary Ca, but was D 3-dependent and tissue specific. The results suggest that the pubertal increase in plasma E 2 can affect Ca absorption from the intestine by increasing the activity of AP.

Effect of dietary carbohydrate and phenotype on sucrase, maltase, lactase, and alkaline phosphatase specific activity in SHR/N-cp rat.

The obese spontaneous hypertensive rat/NIH-corpulent (SHR/N-cp) rat exhibits some of the metabolic and pathologic alterations associated with non-insulin-dependent diabetes mellitus and hypertension. The current study was conducted to investigate the influence of phenotype (ob versus In) and source of dietary carbohydrate (sucrose versus starch) on intestinal sucrase, maltase, lactase, and alkaline phosphatase activity in SHR/N-cp rats. For 3 months, lean and obese male SHR/N-cp rats were fed isocaloric diets containing as the sole source of carbohydrate either 54% cooked corn starch or sucrose. Serum and urine markers for diabetes were observed in obese rats. Wet weight and length of intestines were significantly increased in obese rats compared with lean littermates. Among the intestinal enzymes measured, statistical tests confirmed that sucrase activity was significantly increased (P < 0.01) by both phenotype (ob > In) and feeding a sucrose diet. Diet alone (sucrose > starch) significantly increased (P < 0.05) maltase activity in obese rats, but had no effect on lean rats. Lactase activity was significantly higher (P < 0.05) in obese sucrose-fed rats compared with obese starch-fed and/or lean littermates. Statistical tests revealed that intestinal alkaline phosphatase activity was significantly altered (P < 0.05) by both phenotype and diet. Intestinal alkaline phosphatase was higher in starch-fed lean rats compared with lean littermates fed sucrose and to starch or sucrose-fed obese rats. These results are not indicative of a simple, nonspecific increase in intestinal enzyme activity, since the effects observed in intestinal alkaline phosphatase contrast the effects observed in intestinal sucrase, maltase, and lactase activity. These results indicate that both phenotype and diet alter structural and enzymatic intestinal activities of SHR/N-cp rats. Distinct variations in the observed intestinal enzymatic activities suggest that these enzymes are under the control of genetic, hormonal, and dietary factors. Rationale for these differences are discussed.

The effects of hexavalent chromium on the activity of alkaline phosphatase in the intestine of rainbow trout ( Oncorhynchus mykiss)

This work is a contribution to the study of the effects of hexavalent chromium on intestinal alkaline phosphatase activity in fish. The enzyme activity was studied in intact tissues of rainbow trout ( Oncorhynchus mykiss). incubated at 25°C with paranitrophenyl phosphate. Substrate hydrolysis has an optimum at pH 10 and is linear with time up to, at least, l h. Preincubation at a basic pH in the absence of substrate for 30 min or more, leads to a decrease of the enzyme activity. This inhibition is lower when phosphate is added to the preincubation medium. The mucosal layer has a special influence on V max which is higher when the intestinal tissue is blotted on filter paper. Chromium dichromate leads to a decrease of the enzyme activity when the tissue is first preincubated in the absence of substrate. This inhibition is dependent upon the metal concentration up to 1 mM. At higher concentrations an attenuation of this effect has been shown. Preincubation at alkaline pH stimulates the effect of chromium. The inhibition is time dependent. However, for longer preincubations (60 min) the chromium effect seems to be progressively reversed. Mucus does not protect the enzyme from the metal. Dichromate ions have a special influence on V max and a minor one on the K m, of the enzyme. The substrate (paranitrophenyl phosphate) effectively protects the enzyme even at low concentrations (0.18 mM). Phosphate has the same effect but especially al a high concentration (100 mM). After a reduction by ascorbate, chromium does not inhibit phosphatase activity. The inhibition has been thought to be due to the oxidation of specific molecules. The role of SH groups has been postulated since DTT protects the enzyme, and partially restores its activity after treatment with chromium.

Inanition may Reduce Alkaline Phosphatase Activity in Liver and Intestine of Zinc-Deficient Mice

Zinc-deficiency was induced in mice by feeding a Zn-deficient basal diet (ZD dietary group) containing 9% lipid (6% corn oil, 3% cod liver oil) for 8 wk. Thereafter, the corn oil was withdrawn from the basal diet and a subset of Zn-deficient animals (ZDLR group) was fed this modified low fat diet for another 8 wk. Alkaline phosphatase activity in intestine and liver was compared in these mice and in those allowed ad libitum access to the lipid-adequate Zn-supplemented diet (ZS group), in those pair-fed the Zn-supplemented diet (PF group) and in those fed the lipid-adequate, Zn-deficient diet ad libitum (ZD group). The enzyme activity in both intestine and liver of the ZDLR group was greater than in those of the ZD group and greater than or equal to those of the ZS and PF diet groups. The results of this study suggest that the reduction in alkaline phosphatase in Zn-deficient animals is a response secondary to associated inanition.

The effects of aluminum ingestion on intestinal cadmium absorption, lipid peroxidation and alkaline phosphatase activity

Consumption of dietary aluminum (Al, 2000 or 4000 ppm) for 1 month did not influence mouse body weight. In order to estimate an absorption of cadmium (Cd) from the gastrointestinal tract, mice were intubated twice every 24 h with Cd (CdCl 2). In the Al-supplemented mice, Cd absorption increased rather than decreased. Intestinal Cd and metallothionein concentrations were increased by the Al supplement. Intestinal alkaline phosphatase activity and lipoperoxide concentrations were also enhanced by Al ingestion. Of course, intestinal Al concentration was at a high level in the Al-supplemented groups. However, Al accumulation was not observed in the liver. The increase of Cd absorption may be due to an abnormality of the gut wall caused by the Al. Our results suggest that Al is not inert for animals, even though Al absorption is poor.

Triglyceride fatty acid chain length influences the post prandial rise in serum intestinal alkaline phosphatase activity.

Intestinal alkaline phosphatase (IALP) activity rises following the ingestion of a fat-containing meal. Previous studies on intestinal fluid and lymph have shown that the magnitude of this response is dependent upon fatty acid chain length. To examine this relation in the serum of healthy humans, 10 subjects consumed two standardized fat meals. One meal contained predominantly long chain fatty acid triglycerides, the other contained predominantly medium chain fatty acid triglycerides. Serum IALP activity was measured in serial blood samples using a sensitive immunological assay. IALP activity was ABO blood group and secretor status dependent. The post-prandial rise in serum IALP activity was significantly greater following the long chain fatty acid meal than following the medium chain fatty acid meal. Previous observations of the fatty acid chain length dependency of the IALP response to fat ingestion, therefore, also apply in the serum of healthy humans under normal physiological conditions. Standardized fat meals provide the basis of a useful method for the investigation of the role of IALP in fat absorption.

Serum levels of human alkaline phosphatase isozymes in relation to blood groups

By use of sensitive immunocatalytic assays, based on isozyme specific monoclonal antibodies, the activities of the three main human alkaline phosphatases were determined in serum. The activities were related to ABO blood groups and secretor phenotypes. The activity of intestinal alkaline phosphatase was found to be strongly correlated with ABO blood groups and secretor phenotypes, while neither the placenta alkaline phosphatase activity nor the tissue unspecific alkaline phosphatase activity demonstrated any dependence on blood groups or secretor phenotypes. Non-secretors, independent of ABO blood groups, demonstrated low activities of intestinal alkaline phosphatase in serum, amounting to approximately 20% of the activities in the secretor groups. Within the secretor group, the lowest activities were observed for blood group A (2.8 ± 1.1 IU/l; mean ± SEM) and the highest for blood groups B and O (14.1 ± 1.1 IU/l and 19.0 ± 2.5 IU/l, respectively). These results confirm that the activities of intestinal alkaline phosphatase in serum have to be related both to ABO blood groups and to secretor phenotypes in order to be informative in clinical contexts.

Intestinal origin alkaline phosphatase activity in plasma for differential diagnosis of jaundice.

Intestinal origin alkaline phosphatase activity (ALP) in plasma was measured by a sensitive immunocapture assay in 104 jaundiced patients--84 with intrahepatic and 20 with post-hepatic jaundice. Increased enzyme activities were observed in those with intrahepatic disease and subnormal values in those with post-hepatic disease. At a discriminant level intestinal origin ALP showed a diagnostic sensitivity of 77% for intrahepatic cholestasis, with a diagnostic accuracy of 75% for its differentiation from post-hepatic jaundice. This diagnostic accuracy is not as good as that derived with other techniques--for example, imaging--and the technique is therefore not recommended as a supplement or replacement.

Measurement of Calbindin‐D9K in Small Intestinal Biopsy Specimens of Children

SummaryThe vitamin D dependent intestinal calcium‐binding protein (calbindin‐D9K) was measured by an enzyme‐linked immunoadsorbent assay in small intestinal biopsy specimens from 10 children (aged 15–126 months). The aim was to study the relationship between calcium‐binding protein and age, bone age, and height. The patients were examined due to complaints of chronic diarrhea, but no evidence of malabsorption was found. The amount of calbindin‐D9K per mg of soluble protein in the small intestinal biopsy specimens was higher than previously studied in normal adults. Calbindin‐D9K correlated inversely with chronological age, bone age, and height of the children (p = −0.87, p = −0.66, and p = – 0.66; p &lt; 0.05). A direct correlation was found between calbindin‐D9K and intestinal alkaline phosphatase activity (p = 0.60; p &lt; 0.05). The decline in calbindin‐D9K may indicate that the active vitamin D dependent intestinal calcium absorption decreases during childhood.

Measurement of Calbindin-D9K in Small Intestinal Biopsy Specimens of Children

The vitamin D dependent intestinal calcium-binding protein (calbindin-D9K) was measured by an enzyme-linked immunoadsorbent assay in small intestinal biopsy specimens from 10 children (aged 15-126 months). The aim was to study the relationship between calcium-binding protein and age, bone age, and height. The patients were examined due to complaints of chronic diarrhea, but no evidence of malabsorption was found. The amount of calbindin-D9K per mg of soluble protein in the small intestinal biopsy specimens was higher than previously studied in normal adults. Calbindin-D9K correlated inversely with chronological age, bone age, and height of the children (p = -0.87, rho = -0.66, and rho = -0.66; p less than 0.05). A direct correlation was found between calbindin-D9K and intestinal alkaline phosphatase activity (p = 0.60; p less than 0.05). The decline in calbindin-D9K may indicate that the active vitamin D dependent intestinal calcium absorption decreases during childhood.

Vitamin D receptors and compensatory tissue growth in spontaneously diabetic BB rats.

Untreated diabetic (BB) rats exhibited compensatory intestinal growth which was associated with hyperplasia and was accompanied by an increase in unoccupied vitamin D receptors. Although vitamin D receptors were increased, low circulating 1,25-dihydroxy-vitamin D3 [1,25(OH)2D3] prevented amplification of the action of 1,25(OH)2D3, as evidenced by reductions in calbindin D-9K and alkaline phosphatase activity in the BB rat intestine compared to control. In the kidney, a lesser degree of compensatory growth was observed which was not associated with hyperplasia, and no significant effect of diabetes on vitamin D receptors or calbindin D-28K was observed. These studies suggest tissue-specific changes in 1,25(OH)2D3 metabolism during spontaneous diabetes which may be related to the hyperplasia which occurs during compensatory tissue growth.

Subclinical characteristics of the wasting pig syndrome

The plasma concentrations of cortisol and corticosteroid-binding globulin and the adrenal synthesis capacity of cortisol were analysed in 10-week-old healthy and age-matched wasting or unthrifty pigs. Crypt cell multiplication, villus height and intestinal mucosal alkaline phosphatase (ALP) activity were also investigated. Furthermore, the effect of amperozide, a psychotropic drug with specific effects on emotional behaviour, was analysed for its effect on plasma ALP activity and villus height. Although the wasting pigs exhibited an increased cortisol synthesis capacity, there was a decreased plasma concentration of cortisol in these pigs. Furthermore, the plasma cortisol binding capacity was found to be significantly lowered in wasting pigs. There was also a reduced crypt cell proliferation, a reduced villus height and a decreased ALP activity in the ileal mucosa. Treatment with amperozide resulted in a normalisation of plasma ALP activity in unthrifty pigs, indicating a stimulation of body growth. The results indicate that the growth depression of wasting pigs is most probably a chronic stress syndrome caused by the inability of these animals to cope with the events following weaning and mixing.