scholarly journals Mammalian small intestinal phytase (EC 3.1.3.8)

1983 ◽  
Vol 50 (3) ◽  
pp. 673-678 ◽  
Author(s):  
John R. Cooper ◽  
Helen S. Gowing
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Metal Ions ◽  
Brush Border ◽  
Small Intestinal ◽  
Competing Reactions

1. Phytase (EC 3.1.3.8) concentration has been measured in the small intestineof rat, rabbit, guinea-pig and hamster. Levels varied from 0·12 units (μg phosphorus released/min)/mg protein in the rat to 0·03 units/mg protein in the rabbit.2. The enzyme is localized in the brush border of the small intestine of the rat.3. It is suggested that the levels and location of phytase are an important factor inthe uptake of metals from metal–phytate complexes. Metal ions released in the immediate vicinity of the absorptive surface of the intestine could be absorbed before being rendered insoluble by competing reactions such as hydrolysis.

In vitro Gastrointestinal Models for Prebiotic Carbohydrates: A Critical Review

2019 ◽  
Vol 25 (32) ◽  
pp. 3478-3483 ◽  
Author(s):  
Oswaldo Hernandez-Hernandez
Keyword(s):  
Small Intestine ◽  
Gastrointestinal Tract ◽  
Brush Border ◽  
Critical Review ◽  
In Vitro Digestibility ◽  
Human Gastrointestinal Tract ◽  
Intestinal Brush Border ◽  
Small Intestinal ◽  
Existing Data

Background: In the last decade, various consortia and companies have created standardized digestion protocols and gastrointestinal simulators, such as the protocol proposed by the INFOGEST Consortium, the simulator SHIME, the simulator simgi®, the TIM, etc. Most of them claim to simulate the entire human gastrointestinal tract. However, few results have been reported on the use of these systems with potential prebiotic carbohydrates. Methods: This critical review addresses the existing data on the analysis of prebiotic carbohydrates by different in vitro gastrointestinal simulators, the lack of parameters that could affect the results, and recommendations for their enhancement. Results: According to the reviewed data, there is a lack of a realistic approximation of the small intestinal conditions, mainly because of the absence of hydrolytic conditions, such as the presence of small intestinal brush border carbohydrases that can affect the digestibility of different carbohydrates, including prebiotics. Conclusion: There is a necessity to standardize and enhance the small intestine simulators to study the in vitro digestibility of carbohydrates.

scholarly journals Na+/glucose co-transporter abundance and activity in the small intestine of lambs: enhancement by abomasal infusion of casein

2003 ◽  
Vol 89 (5) ◽  
pp. 573-580 ◽  
Author(s):  
Sameer J. Mabjeesh ◽  
Dafna Guy ◽  
David Sklan
Keyword(s):  
Small Intestine ◽  
Glucose Uptake ◽  
Brush Border ◽  
Brush Border Membrane ◽  
Membrane Vesicles ◽  
Control Group ◽  
Abomasal Infusion ◽  
Group A ◽  
Small Intestinal ◽  
Infusion Period

The purpose of the present study was to determine the effect of abomasal casein infusion on glucose uptake and abundance of the Na+/glucose co-transporter (SGLT1) 1 in the ovine small intestine. Lambs (body weight 35 (SEM 1·0) kg) were surgically fitted with abomasal infusion catheters and were fed diets containing equal portions of wheat hay and cracked maize. Lambs were infused with either 500 g water/d or with 500 g water containing 35 g casein/d. The infusion period lasted 10 d, after which lambs were killed, exsanguinated and eviscerated. Brush border membrane vesicles (BBMV) were prepared using mucosa from different small intestinal regions. Intake and total tract digestibility of nutrients were similar between treatments and averaged 1134, 1142 and 486 g/d and 67, 70, and 94 % for DM, organic matter and non-structural carbohydrates respectively. Crude protein (N×6·25) digestibility was 15 % greater in the casein-infused than control lambs. Glucose uptake to BBMV ranged from 101 to 337 pmol/mg protein per s along the small intestine and was greatest in the mid-section of the small intestine. In the mid-jejunum, glucose uptake was greater (P<0·07) in lambs infused with casein and averaged 120 pmol/mg protein per s compared with 68 pmol/mg protein per s in the control group. SGLT1 affinity was similar between treatments and averaged 104 μM in the different segments of the small intestine of lambs. However, lambs infused with casein exhibited similar values along the small intestine and affinity averaged 106 μm, while in the control group a greater affinity (85 μm) was measured in the mid-jejunum. SGLT1 protein abundance was correlated with glucose uptake in the BBMV in the casein-treated lambs, but not in the control group. These results suggest that glucose uptake along the small intestine of lambs is influenced by casein or its derivatives in the small intestine via SGLT1 affinity and activity at the brush border membrane, and that SGLT1 activity may be regulated by post-translational events affected by amino acids and peptides.

Evidence that neuronally released vasoactive intestinal polypeptide inhibits the release of serotonin from enterochromaffin cells of the guinea pig small intestine

1991 ◽  
Vol 124 (2) ◽  
pp. 203-207 ◽  
Author(s):  
Kurt Racké ◽  
Harald Schwörer ◽  
Denis V. Agoston ◽  
Heinz Kilbinger
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Vasoactive Intestinal Polypeptide ◽  
Inhibitory Effect ◽  
Good Evidence ◽  
Muscarine Receptors ◽  
Intestinal Segments ◽  
Hydroxyindoleacetic Acid ◽  
Small Intestinal ◽  
Intestinal Polypeptide

Abstract. Isolated small intestinal segments of the guinea pig were arterially perfused and the release of serotonin (5-hydroxytryptamine) and 5-hydroxyindoleacetic acid into the portal venous effluent was determined by HPLC with electrochemical detection. Test substances were intra-arterially applied. The muscarine receptor agonist oxotremorine (1 μmol/l inhibited the release of 5-hydroxytryptamine by about 50%. In the presence of the neurotoxin tetrodotoxin, oxotremorine enhanced the release of 5-hydroxytryptamine by 145%, indicating that the inhibitory effect of oxotremorine was mediated by the release of a neurotransmitter. Exogenous vasoactive intestinal polypeptide ( 1-100 pmol/l inhibited the release of 5-hydroxytryptamine by about 50%, an effect antagonized by a specific antibody to vasoactive intestinal polypeptide. This antibody to vasoactive intestinal polypeptide, on its own, had no effect on the release of 5-hydroxytryptamine. However, it prevented the inhibitory effect of oxotremorine. In the presence of the antibody to vasoactive intestinal polypeptide, unlike in the presence of tetrodotoxin, oxotremorine did not stimulate the release of 5-hydroxytryptamine. In conclusion, activation of neuronal muscarine receptors in the guinea pig small intestine enhances the release of several neurotransmitters which can inhibit the release of 5-hydroxytryptamine. The present experiments provide good evidence that vasoactive intestinal polypeptide is one of them.

scholarly journals Glucose metabolism in the mucosa of the small intestine. A study of hexokinase activity

1968 ◽  
Vol 109 (1) ◽  
pp. 35-42 ◽  
Author(s):  
L M Srivastava ◽  
P. Shakespeare ◽  
G. Hübscher
Keyword(s):  
Small Intestine ◽  
Lactate Dehydrogenase ◽  
Glucose Metabolism ◽  
Guinea Pig ◽  
Intestinal Mucosa ◽  
Brush Border ◽  
Deae Cellulose ◽  
Mitochondrial Fraction ◽  
Type Ii ◽  
Hexokinase Activity

1. The intracellular distribution of hexokinase activity was studied in the mucosa of rat and guinea-pig small intestine. In the rat 60% and in the guinea pig 45% of the hexokinase activity of homogenates were recovered in a total particulate fraction that contained only 5–17% of the homogenate activity of hexose phosphate isomerase, pyruvate kinase, lactate dehydrogenase and overall glycolysis (formation of lactate from glucose). 2. Fractionation of homogenates from guineapig small intestine showed that the particulate hexokinase activity was chiefly in the mitochondrial fraction with a small proportion in the nuclei plus brush-border fraction. 3. After chromatography of the particle-free supernatants on DEAE-cellulose, hexokinase types I and II were determined quantitatively. No evidence was obtained for the presence of hexokinase type III or glucokinase. In the preparations from guinea pigs, hexokinase types I and II amounted to 69% and 31% respectively of the eluted activity; the corresponding values for preparations from rats were 5·8% and 94·2%. 4. Total and specific hexokinase activities decreased significantly in homogenates and particle-free supernatants prepared from the intestinal mucosa of rats starved for 36hr. and increased again after re-feeding. The decrease in hexokinase activity in the particle-free supernatant from starved rats was chiefly due to a decrease in the type II enzyme.

EndothelinB receptor on guinea pig small intestinal smooth muscle cells

1992 ◽  
Vol 262 (2) ◽  
pp. G308-G311 ◽  
Author(s):  
M. Yoshinaga ◽  
Y. Chijiiwa ◽  
T. Misawa ◽  
N. Harada ◽  
H. Nawata
Keyword(s):  
Smooth Muscle ◽  
Small Intestine ◽  
Guinea Pig ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Binding Characteristics ◽  
Longitudinal Smooth Muscle ◽  
Etb Receptor ◽  
Small Intestinal ◽  
Functional Receptor

We investigated the binding characteristics of the endothelin (ET) receptor and the mechanism by which ET induces contraction of longitudinal smooth muscle cells of the guinea pig small intestine by using vasoactive intestinal contractor (VIC), a mouse variant of ET-2. A functional receptor for VIC was found to exist on longitudinal smooth muscle cells. These cells showed a similar binding of and contractile response to ET-1, ET-2, and ET-3. Inhibitors of both intracellular and extracellular Ca2+ movement attenuated the VIC-induced contraction of longitudinal smooth muscle cells. These results suggest that smooth muscle cells of the guinea pig small intestine express the ETB receptor that primarily mediates the contractile effect on smooth muscle cells. In addition, ET-induced contraction depends on intracellular as well as extracellular Ca2+.

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