Transport of butyric acid in vascularly perfused anuran small intestine: importance of pH and anion transport

1986 ◽  
Vol 250 (4) ◽  
pp. G469-G474
Author(s):  
D. Hollander ◽  
E. M. Gerard ◽  
C. A. Boyd
Keyword(s):  
Small Intestine ◽  
Butyric Acid ◽  
Nonlinear Function ◽  
Anion Transport ◽  
Transport Protein ◽  
Disulfonic Acid ◽  
Flux Analysis ◽  
Acid Transport ◽  
Distal Small Intestine ◽  
Proximal Small Intestine

Butyric acid transport was studied in the isolated, vascularly perfused frog small intestine. At luminal butyric acid concentrations of 5-50 mM, absorption was a nonlinear function of the luminal concentration, whereas the relationship of absorption to concentration remained linear at 0-1,000 microM. The most important factor regulating the rate and direction of butyric acid transport was the pH. We used unidirectional flux analysis to determine net transport across the epithelium while the pH of the luminal or vascular compartments was changed. We found a four- to fivefold decrease in butyric acid transport into the portal circulation as the lumen pH was increased from 6.0 to 8.0. The pH of the vascular perfusate influenced the vascular-to-lumen transport of butyric acid in the same proportions. The second important regulatory factor of butyric acid transport was the 4,4'-diisothiocyananostilbene-2,2'-disulfonic acid (DIDS)-sensitive anion transport protein. DIDS added to the lumen at 10(-6) M decreased butyric acid transport by approximately 40% at pH 7.4. DIDS also inhibited butyric acid transport when added to the vascular perfusate or when transport was measured in a vascular-to-lumen direction. We suggest that, at the relatively low pH of the proximal small intestine, butyric acid becomes protonated and lipophilic and is mainly transported directly through the cell membrane. At the more alkaline pH of the distal small intestine butyric acid is in the ionized form and transport by the DIDS-sensitive anion transport protein may predominate.

Variation in Rotavirus Virulence: A Comparison of Pathogenesis in Calves between Two Rotaviruses of Different Virulence

1993 ◽  
Vol 30 (3) ◽  
pp. 223-233 ◽  
Author(s):  
G. A. Hall ◽  
J. C. Bridger ◽  
K. R. Parsons ◽  
R. Cook
Keyword(s):  
Small Intestine ◽  
Virulent Strain ◽  
Villus Height ◽  
Distal Small Intestine ◽  
Cytopathic Effects ◽  
Proximal Small Intestine ◽  
Viral Particles ◽  
Virulent Virus ◽  
The Mean ◽  
Spread Of Infection

Variation in virulence between two bovine rotaviruses was investigated using ten female and ten male 10-day-old gnotobiotic calves of five breeds or cross breeds that were inoculated with a virulent strain or a strain of low virulence. Similar numbers of infectious viral particles were detected in feces of calves inoculated with either virus, but diarrhea, xylose malabsorption, and reduction of villus height occurred only after inoculation with virulent virus. The mean percentage of the area of the villus epithelium per villus immunostained for rotavirus antigen was eight times greater in calves inoculated with virulent virus, and the mean percentage of villi on which immunostained enterocytes were detected was twice as large in calves inoculated with virulent virus than in calves inoculated with the virus of low virulence. Mean crypt death and mean crypt cell production rates were increased after inoculation with either virus. Virulence was associated with extensive spread of infection through the small intestine, preferential colonization of the proximal small intestine, and marked damage to enterocytes and villi. The virus of low virulence infected the proximal small intestine poorly, and although it infected more enterocytes in the mid and distal small intestine and replicated in them, causing cytopathic effects, it did not damage intestinal structure and affect function.

Intestinal myoelectrical activity and transit time in chronic portal hypertension

1992 ◽  
Vol 263 (4) ◽  
pp. G474-G479 ◽  
Author(s):  
J. J. Stewart ◽  
H. D. Battarbee ◽  
G. E. Farrar ◽  
K. W. Betzing
Keyword(s):  
Small Intestine ◽  
Portal Hypertension ◽  
Portal Vein ◽  
Transit Time ◽  
Experimental Period ◽  
Phase Iii ◽  
Adult Rats ◽  
Myoelectrical Activity ◽  
Distal Small Intestine ◽  
Proximal Small Intestine

This study was designed to determine the effects of portal hypertension on intestinal myoelectrical activity and propulsion. In a single surgery, adult rats were implanted with a serosal electrode at each quarter of the small intestine, and portal hypertension was produced by calibrated constriction of the portal vein. To determine intestinal transit, portal vein-stenosed (PVS) and sham-operated animals were chronically implanted with a catheter in the proximal small intestine. Transit time was determined by measuring the progression of radioactive chromium along the bowel. Studies were conducted 6, 9, and 14 days after surgical preparation. Portal hypertension was associated with both transient and persistent changes in intestinal myoelectrical activity during the experimental period. Slow wave frequency was significantly reduced in the proximal small intestine on all test days and in the distal small intestine on day 14. Occurrence of the migrating myoelectric complex was reduced on days 6 and 9. Phase III amplitude was significantly reduced in the distal small intestine on all test days. Changes in intestinal myoelectrical activity in PVS animals were not associated with measurable changes in intestinal propulsion. The results suggest that both transient and persistent changes in intestinal myoelectrical activity occur during the 2-wk period after portal vein stenosis. The functional significance of the changes is unknown.

Localization of cholesterol synthesis along villus-crypt axis in diabetic rats

1987 ◽  
Vol 253 (3) ◽  
pp. G336-G344
Author(s):  
K. R. Feingold ◽  
A. H. Moser
Keyword(s):  
Small Intestine ◽  
Cholesterol Synthesis ◽  
Cell Mass ◽  
Diabetic Rats ◽  
Major Site ◽  
Distal Small Intestine ◽  
Proximal Small Intestine ◽  
Cell Layers ◽  
Cell Fractions ◽  
Crypt Cells

In diabetic animals cholesterol synthesis is increased in the small intestine, and this increase occurs in all segments along the duodenal-ileal axis. In the present study we have determined the sites along the villus-crypt axis in which cholesterol synthesis is increased. In diabetic animals cholesterol synthesis is increased in the proximal small intestine, and this is chiefly due to an increased synthesis in the crypt cells. In the midintestine cholesterol synthesis is increased in all cell fractions, but again the crypt cells are the major site accounting for the increase. In the distal small intestine synthesis is increased in all cell fractions, but the increase is greatest in the upper villus cells. Thus the basis for the increase in intestinal cholesterol synthesis in diabetic animals is dependent on location. Additionally, in the proximal small intestine the increase in synthesis is due to an increased mass of cells, whereas in the distal small intestine the increase is due to an increased synthesis per unit of tissue. In cholesterol-fed diabetic animals we observed a decrease in cholesterol synthesis in the proximal and midintestine that was due to a decrease in synthesis in all cell fractions. This decrease in synthesis is accounted for by a decrease in synthesis per unit of tissue. Restricting food intake in the diabetic animals decreased cholesterol synthesis in all cell layers, and this decrease is due to a decrease in cell mass.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The development of arylsulphatase in the small intestine of the rat

1969 ◽  
Vol 114 (2) ◽  
pp. 343-350 ◽  
Author(s):  
S. H. Danovitch ◽  
L. Laster
Keyword(s):  
Small Intestine ◽  
Specific Activity ◽  
Sprague Dawley ◽  
Adult Rats ◽  
Ph Optimum ◽  
Distal Small Intestine ◽  
Sprague Dawley Rats ◽  
Proximal Small Intestine ◽  
Liver And Kidney ◽  
Old Rats

1. Arylsulphatase activity was measured in stomach, proximal and distal third of small intestine, colon, liver and kidney of foetal and neonatal Sprague–Dawley rats and Swiss mice, with nitrocatechol sulphate as substrate. 2. The specific activity in the distal small intestine, but not in the stomach, proximal small intestine or colon, increased about fourfold between 5 and 16 days after birth in both conventional and germ-free rats. 3. No comparable increase occurred in the distal small intestine of the mouse. 4. The specific activity of acid phosphatase in the distal small intestine of the rat rose only slightly when the arylsulphatase activity increased. 5. The pH optimum and Michaelis constant of arylsulphatase activity of the distal small intestine were similar for 1-day-old, 9-day-old and adult rats. 6. When extracts of distal small intestine of 1-day-old and 9-day-old rats were incubated together, the arylsulphatase activities were additive.

Evidence against luminal one-for-one Cl(-)-HCO-3 exchange in urodele small intestine

1986 ◽  
Vol 251 (2) ◽  
pp. G230-G236 ◽  
Author(s):  
J. F. White
Keyword(s):  
Small Intestine ◽  
Anion Transport ◽  
Disulfonic Acid ◽  
Transport Mechanisms ◽  
Coupling Ratio ◽  
Indirect Measures ◽  
Transport Inhibitors ◽  
Absorptive Flux ◽  
Disulfonic Stilbenes

The ratio of Cl- absorbed to HCO3- secreted by the in vitro small intestine of Amphiuma was measured using 36Cl and titration. The aim was to estimate the stoichiometry and thereby elucidate the underlying transport mechanisms. For every mole of HCO3- secreted 1.8 mol of Cl- underwent net absorption. Indirect measures of net Cl- absorption and HCO3- secretion were validated. Several known and putative Cl- transport inhibitors were examined for their ability to inhibit the anion transport events. Disulfonic stilbenes [4-acetamido-4'-isothiocyanostilbene-2',2'-disulfonic acid and 4,4'-diisothiocyano-2,2'-disulfonate stilbene (DIDS)] and the diuretics piretanide and furosemide inhibited the Cl- absorptive flux (JClm----s) and simultaneously the HCO3- secretory flux (JHCO3-). The diuretics acetazolamide and bumetanide also reduced JHCO3- and JClm----s, although the latter effect was not statistically significant. The ratio of inhibition, delta JClm----s/delta JHCO3-, varied from 1.2 to 1.8 for the different inhibitors. The presence of Cl(-)-HCO3- exchange at the serosal membrane was deduced from the reduction of JClm----s and JHCO3- by serosally added stilbenes, the reduction of Cl- absorption when serosal Cl- was replaced (reduced Cl(-)-Cl- exchange), inhibition of the secretory-to-mucosal Cl- flux by serosal stilbenes, and enhancement of JHCO3- when serosal medium HCO3- was elevated. Addition of DIDS to the mucosal medium did not alter the secretory flux. The observations are not consistent with one-for-one exchange of Cl- for HCO3- at the mucosal membrane. Other possible mechanisms including rheogenic Cl- uptake in parallel with electrodiffusional efflux of HCO3- are discussed. The observed coupling ratio is compatible with a one-for-one exchange of Cl- for HCO3- at the serosal membrane.

Age- and tissue-specific induction of NHE3 by glucocorticoids in the rat small intestine

2000 ◽  
Vol 278 (4) ◽  
pp. C629-C637 ◽  
Author(s):  
Pawel R. Kiela ◽  
Yigit S. Guner ◽  
Hua Xu ◽  
James F. Collins ◽  
Fayez K. Ghishan
Keyword(s):  
Small Intestine ◽  
Glucocorticoid Receptor ◽  
Western Blot ◽  
Mrna Level ◽  
Rat Small Intestine ◽  
Adult Rats ◽  
Tissue Specific ◽  
Distal Small Intestine ◽  
Proximal Small Intestine ◽  
Specific Induction

Of the two known apical isoforms of the Na+/H+ exchanger (NHE) family, only the NHE3 gene is regulated by glucocorticoids. The aim of these studies was to investigate the mechanisms underlying the effects of methylprednisolone (MP) on expression of NHE3 in the proximal and distal small intestine of suckling and adult rats. Immunoblots showed that the glucocorticoid responsiveness in the proximal small intestine was greatest in suckling animals (NHE3/β-actin: 0.43 ± 0.09 control vs. 1.57 ± 0.15 MP; P < 0.001), and responsiveness decreased with age with no effect in adults (0.56 ± 0.14 vs. 0.64 ± 0.17). Distal small intestine was responsive only in adult rats (0.49 ± 0.13 vs. 1.65 ± 0.09; P < 0.001). This pattern was confirmed at the mRNA level and by 22Na+ uptake. Western blot and [3H]dexamethasone mesylate binding showed that the responsiveness of NHE3 to glucocorticoids is directly related to the expression of glucocorticoid receptor (GR) in the small intestine. These studies suggest that loss and gain of glucocorticoid responsiveness in the proximal and distal small intestine, respectively, are related to age- and segment-dependent expression of GR.

scholarly journals INTESTINAL TRANSPORT OF ANTIBODIES IN THE NEWBORN RAT

1973 ◽  
Vol 58 (1) ◽  
pp. 189-211 ◽  
Author(s):  
Richard Rodewald
Keyword(s):  
Small Intestine ◽  
Cell Surface ◽  
Apical Cell ◽  
Intestinal Transport ◽  
Coated Vesicles ◽  
Neonatal Rat ◽  
Intercellular Spaces ◽  
Newborn Rat ◽  
Distal Small Intestine ◽  
Proximal Small Intestine

Evidence has been reported that the proximal small intestine of the neonatal rat selectively transports antibodies into the circulation. This study describes the morphology of the absorptive epithelial cells in this region of the intestine and their transport of several immunoglobulin tracers: ferritin-conjugated immunoglobulins (IgG-Ft) and antiperoxidase antibodies. Cells exposed to rat IgG-Ft bound the tracer on the membrane of tubular invaginations of the apical cell surface. Tubular and coated vesicles within the cell also contained the tracer, as did the intercellular spaces. Uptake of tracer was highly selective and occurred only with rat or cow IgG-Ft; when cells were exposed to chicken IgG-Ft, ferritin-conjugated bovine serum albumin, or free ferritin, tracer did not enter the cell or appear in the intercellular spaces. Experiments with rat and chicken antiperoxidase showed a similar selective uptake and transport of only the homologous antibody. When cells from the distal small intestine were exposed to the tracers, all tracers were absorbed nonselectively but none were released from the cells. Cells from the proximal small intestine of the 22-day-old rat failed to absorb even rat IgG-Ft. A model is presented for selective antibody transport in proximal cells of the neonatal rat in which antibodies are selectively absorbed at the apical cell surface by pinocytosis within tubular vesicles. The antibodies are then transferred to the intercellular space within coated vesicles. Distal cells function only to digest proteins nonselectively.

scholarly journals Localization of Astrovirus in Experimentally Infected Turkeys as Determined by In Situ Hybridization

2002 ◽  
Vol 39 (5) ◽  
pp. 595-598 ◽  
Author(s):  
E. Behling-Kelly ◽  
S. Schultz-Cherry ◽  
M. Koci ◽  
L. Kelley ◽  
D. Larsen ◽  
...  
Keyword(s):  
Small Intestine ◽  
In Situ Hybridization ◽  
Experimental Period ◽  
Intestinal Epithelial ◽  
Distal Small Intestine ◽  
Turkey Poults ◽  
Proximal Small Intestine ◽  
Crypt Hyperplasia ◽  
Negative Sense

Twenty-one 3-day-old turkey poults from British United Turkeys of America were orally inoculated with a recently characterized astrovirus, TAstV-2, isolated from turkeys with poult enteritis and mortality syndrome. At 1, 2, 3, 4, 5, 7, and 9 days postinfection (dpi), three inoculated birds were euthanatized, and tissues (intestines, spleen, bursa, and thymus) were collected immediately into 10% neutral buffered formalin. Inoculated birds were diarrheic by 3 dpi, and frothy feces persisted throughout the experimental period. Histologically, there was only slight evidence of enteric damage, which was characterized by mild epithelial necrosis, lamina propria infiltrates, minimal villus atrophy, and mild crypt hyperplasia. In situ hybridization, using a negative sense digoxigenin-labeled riboprobe to the capsid gene of TAstV-2, revealed viral RNA in intestinal epithelial cells at the basal margins of the villi, in distal small intestine, and in cecum at 2 dpi, with subsequent extension to epithelium of the large intestine and proximal small intestine (3–5 dpi). Minimal virus remained by 9 dpi.

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