On the Mechanism of Isosmotic Transport Across the Small Intestine. The Composition of the Absorbate Transported from a Mucosal Solution made Hypertonic by the Addition of Mannitol

1973 ◽  
Vol 51 (2) ◽  
pp. 130-138 ◽  
Author(s):  
P. K. Dinda ◽  
Marjorie Beck ◽  
I. T. Beck
Keyword(s):  
Small Intestine ◽  
Solute Transport ◽  
Fluid Transport ◽  
Linear Increase ◽  
Mucosal Surface ◽  
Bathing Solution ◽  
Serosal Side ◽  
Hypertonic Solutions ◽  
Mucosal Side

Experiments were performed to investigate the mechanism by which the fluid transported across the small intestine becomes isosmotic with the mucosal solution when the latter is made hypertonic by the addition of a poorly absorbed substance. The mid small intestine of the hamster was isolated and everted. The mucosal surface of the control preparation was bathed with an isotonic Krebs–Ringer bicarbonate solution containing 10 mM glucose (KRBSG) (292 mOsmol/kg). The mucosal surface of the experimental preparations was bathed with one of the hypertonic solutions. These hypertonic solutions were prepared by the addition of 1, 50, 100, or 150 mM mannitol to KRBSG. No bathing solution was placed on the serosal side of these preparations, so that the fluid transported across the intestine, undiluted by a bathing solution (absorbate), could be collected on the serosal side. Results show that the absorbate was always isosmotic with the mucosal solution. In the experimental preparations, as compared to the absorption of other solutes, mannitol was poorly absorbed, even though its concentration in the absorbate sometimes reached 35% of its concentration in the mucosal solution. The small amount of mannitol found in the absorbate was never sufficient to render the absorbates isosmotic with hypertonic mucosal solutions. The absorbate became isosmotic with the mucosal solution due to an increased concentration of other solutes transported from the mucosal side. Increasing the osmolality of the mucosal solution progressively from 292 to 442 mOsmol/kg caused a linear increase in the concentration of Na, K, glucose, and mannitol in the absorbate, but, except for mannitol, the net amount of these substances transported (per gram dry tissue) to the serosal side decreased linearly. The transport of fluid also decreased. Our data further indicate that the ratio of fluid and solute transport progressively decreased with the increase in osmolality of the mucosal solution. Therefore, it appears that when the mucosal solution is made hypertonic by the addition of a poorly absorbed substance, the absorbate becomes isosmotic with the hypertonic mucosal solution by means of a greater diminution of fluid transport than of solute transport.

On the Mechanism of Isoosmotic Transport of Fluid Across the Small Intestine. The Effect of the Staverman Reflection Coefficient of the Solute Used to Increase the Osmolality of the Mucosal Solution on the Composition of the Absorbate

1974 ◽  
Vol 52 (1) ◽  
pp. 96-104 ◽  
Author(s):  
I. T. Beck ◽  
P. K. Dinda
Keyword(s):  
Small Intestine ◽  
Reflection Coefficient ◽  
Solute Transport ◽  
Linear Increase ◽  
Water Soluble ◽  
Potential Difference ◽  
Reflection Coefficients ◽  
Serosal Side ◽  
Linear Decrease ◽  
Erythritol And Mannitol

The objective of the present study was to investigate the mechanism by which the fluid transported across the small intestine becomes isoosmotic with the mucosal solution. The osmolality of the mucosal solution of a unilateral preparation (the serosal side was not bathed) was increased with water soluble, nonelectrolyte solutes of different Staverman reflection coefficients (σ), and the composition of the undiluted absorbate was studied. The solutes ('hyperosmotic agents') used were formamide, urea, erythritol, and mannitol. In a series of separate experiments, utilizing a method based on potential difference depression, we found that the σ's of these solutes in the hamster small intestine were 0.26, 0.85, 0.93, and 1.00, respectively. Our data on transport across the unilateral preparation showed that when the intestine was incubated in an isotonic mucosal solution (Krebs–Ringer bicarbonate solution containing 10 mM glucose, 292 mosmol/kg), the absorbate was essentially isotonic, although its composition was significantly different from that of the mucosal solution. When the osmolality of the mucosal solution was increased to 342, 392, or to 442 mosmol/kg with any of the hyperosmotic agents, the absorbate was always isoosmotic with the mucosal solution. With formamide (low σ) as the hyperosmotic agent, the concentration of electrolytes and glucose in the absorbate was the same as that in the absorbate of the control preparation (incubated in the isotonic mucosal solution), and the transported fluid became isoosmotic with the mucosal solution exclusively due to the presence of formamide in the absorbate. When the osmolality of the mucosal solution was increased with urea, erythritol, or mannitol, the concentration of these hyperosmotic agents in the absorbate decreased linearly with the increase in their σ, and the absorbate became isoosmotic with the mucosal solution due to a linear increase in the concentration of electrolytes and glucose. In addition, we found that the transport of fluid, solutes, and fluid/solute (ml/mmol per gram dry intestine) decreased linearly with the increase in σ of the hyperosmotic agents. Further calculation of the data showed that the increase in the concentration of electrolytes and glucose with the increase in σ of the hyperosmotic agents was almost exclusively due to a linear decrease in fluid/solute transport.

Fluid Movement Across the Wall of the Small Intestine in Vitro

1956 ◽  
Vol 187 (2) ◽  
pp. 244-246 ◽  
Author(s):  
T. Hastings Wilson
Keyword(s):  
Small Intestine ◽  
Sodium Chloride ◽  
Saline Solution ◽  
Isotonic Saline ◽  
Bicarbonate Secretion ◽  
Serosal Side ◽  
Fluid Movement ◽  
Mucosal Side

Small sacs of everted jejunum of the hamster were incubated in sugar free bicarbonate-saline solution in vitro. Both fluid and sodium chloride moved across the wall of the intestine from mucosal to serosal side. This movement of isotonic saline solution across the intestine was inhibited anaerobically. A small bicarbonate secretion was noted in the direction of serosal to mucosal side.

Sodium and Water Transport Across the Jejunum of Fasted Rats

1973 ◽  
Vol 51 (6) ◽  
pp. 405-409 ◽  
Author(s):  
Ivan T. Beck ◽  
P. K. Dinda
Keyword(s):  
Sodium Transport ◽  
Fluid Transport ◽  
Electrical Potential ◽  
Electrical Potential Difference ◽  
Serosal Side ◽  
Concomitant Increase ◽  
Net Flux ◽  
Unidirectional Fluxes ◽  
Mucosal Side ◽  
Fasted Rats

The effect of 72 h fasting on the transmural electrical potential difference (P.D.), the unidirectional fluxes, and the net flux of sodium and the net transport of fluid across the jejunum of rats was investigated. Everted jejunal segments were incubated in 12 ml of Krebs–Ringer bicarbonate solution containing 5.55 mM glucose on either side for 1 h at 37 °C. Seventy-two hours fasting caused a 63% increase in the transmural P.D., a 60% increase in the flux of Na from the mucosal to the serosal side, and a 48% increase in the flux of Na from the serosal to the mucosal side. The net mucosal to serosal Na flux increased by 97%. There was also a 41% increase in fluid transport across the intestine of fasted rats. The concomitant increase in sodium and fluid transport and in transmural P.D. is consistent with the current hypotheses of fluid and sodium transport.

Effects of metabolic disturbances on potential difference across intestinal wall of rat

1963 ◽  
Vol 204 (1) ◽  
pp. 105-108 ◽  
Author(s):  
Masashi Sawada ◽  
Tomoaki Asano
Keyword(s):  
Small Intestine ◽  
Low Temperature ◽  
Intestinal Wall ◽  
Potential Difference ◽  
Rapid Decline ◽  
Serosal Side ◽  
Metabolic Disturbances ◽  
Temperature Dependent ◽  
Mucosal Side

The potential difference across the wall of the small intestine was determined in vitro under a variety of conditions using rats. When the normal Ringer's containing 200 mg/100 ml glucose was applied on both sides of the wall, the potential difference attained 5–9 mv, the serosal side being positive. The potential difference was temperature dependent, becoming reduced at low temperature, the temperature coefficient being 1.7 between 40 and 34 C. The potential difference was inhibited with 0.1 mm monoiodoacetic acid, 1 mm sodium azide, 0.1 mm dinitrophenol, and 50 µm ouabain applied on the mucosal side. Withdrawal and restitution of 200 mg/100 ml glucose on the mucosal side induced a rapid decline and recovery of the potential difference. The lowered potential difference was partially recovered by 200 mg/100 ml galactose but not by sorbitol.

scholarly journals 146 Nutritional Advances in Fetal and neonatal development: effect of fatty acid supplementation

2020 ◽  
Vol 98 (Supplement_3) ◽  
pp. 121-122
Author(s):  
Alejandro E Relling
Keyword(s):  
Small Intestine ◽  
Fatty Acid ◽  
Plasma Insulin ◽  
Linear Increase ◽  
Late Gestation ◽  
Insulin Concentration ◽  
Plasma Insulin Concentration ◽  
Pufa Supplementation ◽  
Epa And Dha ◽  
Offspring Growth

Abstract Data from a series of experiments demonstrates that maternal supply of polyunsaturated fatty acids, particularly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), during late gestation affects offspring growth. The increase in growth is independent on the fatty acid supplemented during the growing or finishing phase of the offspring; but it is sex dependent. Dam PUFA supplementation increases wether growth. Supplementation with EPA and DHA to pregnant ewes and to their offspring after weaning showed a treatment interaction in mRNA concentration of hypothalamic neuropeptides associated with dry matter intake (DMI) regulation. A dose increased in EPA and DHA in pregnant ewe diets shows a linear increase in growth, but a quadratic change in DMI or feed efficiency; growth was associated with a linear increase in plasma glucose concentration and a linear decrease in plasma ghrelin concentration. In lambs born from ewes supplemented with different sources of FA during a glucose tolerance test; males’ plasma insulin concentration increased as FA unsaturation degree increased in the dam diet, the opposite happened with females’ plasma insulin concentration. Recent data from our lab showed that the supplementation with EPA and DHA during the last third of gestation to pregnant ewes increased liver and small intestine global DNA methylation and small intestine transporters for amino acids in the fetus. Despite EPA and DHA during late gestation increase growth in the offspring; when EPA and DHA were supplemented in early gestation, offspring growth was lesser that lambs born from ewes supplemented a saturated and monounsaturated lipid. The reason for the difference in results it is not clear. However, more studies focusing in some aspect of the biology will help to understand what specific fatty acid needs to be supplemented at different stages of gestation to improve offspring growth.

scholarly journals Absorption and metabolism of volatile fatty acids by rumen and omasum

2012 ◽  
Vol 36 (1) ◽  
pp. 93-99 ◽  
Author(s):  
João Luiz Pratti Daniel ◽  
João Chrysostomo de Resende Júnior
Keyword(s):  
Fatty Acids ◽  
Mitotic Index ◽  
Volatile Fatty Acids ◽  
Diffusion Chamber ◽  
Serosal Side ◽  
Buffer Solution ◽  
Mucosal Side ◽  
Over Time ◽  
Fractional Absorption

Volatile fatty acids (VFA) absorption and metabolic capacity of rumen and omasum were compared, in vitro. Fragments of rumen wall and omasum laminae were taken from eight adult crossbred bovines. An isolated fragment of the mucosa was fitted in a tissue diffusion chamber. Valeric acid and CrEDTA were added to ruminal fluid and placed on the mucosal side and buffer solution was placed on the serosal side. Fractional absorption rates were measured by exponential VFA:Cr ratio decay over time. Metabolism rate was determined as the difference between VFA absorbed and VFA which appeared on the serosal side over time. Mitotic index was higher in omasum (0.52%) than in rumen epithelium (0.28%). VFA fractional absorption rate was higher in omasum (4.6%/h.cm²) than in rumen (0.4%/h.cm²). Acetate, propionate, butyrate, and valerate showed similar fractional absorption rates in both fragments. Percentage of metabolized acetate and propionate was lower than butyrate and valerate in both stomach compartments. In the rumen, individual VFA metabolism rates were similar (mean of 7.7 , but in the omasum, valerate (90.0 was more metabolized than butyrate (59.6 propionate (69.8 and acetate (51.7 . Correlation between VFA metabolism and mitotic index was positive in the rumen and in the omasum. In conclusion, VFA metabolism and absorption potential per surface of the omasum is higher than that of the rumen. Variations on rumen and omasum absorption capacities occur in the same way, and there are indications that factors capable of stimulating rumen wall proliferation are similarly capable of stimulating omasum walls.

Effect of pH on chloride absorption in the flounder intestine

1988 ◽  
Vol 255 (2) ◽  
pp. G247-G252 ◽  
Author(s):  
A. N. Charney ◽  
J. I. Scheide ◽  
P. M. Ingrassia ◽  
J. A. Zadunaisky
Keyword(s):  
Small Intestine ◽  
Short Circuit ◽  
Ph Effect ◽  
Short Circuit Current ◽  
Bathing Solution ◽  
Solution Ph ◽  
Transport Pathway ◽  
Ussing Chambers ◽  
Chloride Absorption ◽  
In Series

Chloride absorption in the small intestine of the winter flounder, Pseudopleuronectes americanus, is reported to be sensitive to ambient pH. We studied this sensitivity in isolated stripped intestinal mucosa mounted in modified Ussing chambers. Unidirectional 36Cl fluxes (JClm----s, JCls----m) were measured under short-circuited conditions in bathing solutions containing various combinations of HCO3- (0-20 mM), partial pressure of CO2 (0-36 mmHg), and pH (6.77-7.85). We found that JClm----s, net 36Cl flux (JClnet), and short-circuit current (Isc) increased and JCls----m decreased predominately in response to increases in bathing solution pH. There was a linear relationship between pH and both JClnet (r = 0.92, P less than 0.01) and Isc (r = 0.96, P less than 0.005) between pH 6.77 and 7.74. The pH effect was completely reversible, did not require either CO2 or HCO3-, and was not affected by the presence of mucosal barium at 1 mM. Mucosal bumetanide (0.1 mM) completely inhibited the pH effect. These data suggest that the process by which Cl- is absorbed in the flounder intestine is sensitive to pH. The data do not indicate whether pH affects Na+-K+-2Cl- cotransport or a Cl- transport pathway in series with this process. The direction of Cl- absorption in response to pH contrasts with inverse relation of pH and Cl- absorption in mammalian small intestine.

scholarly journals Amino acids and carbohydrates absorption by Na+-dependent transporters in the pyloric ceca of Hoplias malabaricus (Erythrinidae)

2001 ◽  
Vol 31 (5) ◽  
pp. 793-797 ◽  
Author(s):  
Vania Lucia Pimentel Vieira ◽  
Bernardo Baldisserotto
Keyword(s):  
Amino Acids ◽  
Optimal Growth ◽  
Serosal Side ◽  
Carbohydrate Absorption ◽  
Hoplias Malabaricus ◽  
Main Site ◽  
Adequate Diet ◽  
Mucosal Side ◽  
Pyloric Ceca

Information about amino acids and carbohydrate absorption in fish is important to formulate an adequate diet to obtain optimal growth. Therefore, the objective of this study was to investigate if Na+-dependent transporters are involved on the absorption of glycine, L-glutamine, L-leucine, L-lysine, L-proline, L-alanine, and the carbohydrates fructose and glucose in the pyloric ceca of Hoplias malabaricus. The pyloric ceca were mounted in a system of continuous perfusion "in vitro". Amino acids and carbohydrates were placed on the mucosal side at concentrations of 10, 20, and 40mM. The serosal side of the pyloric ceca was positive in relation to the mucosal side. The addition of glycine, L-glutamine, L-leucine, L-lysine, L-proline (all tested concentrations), and glucose (at concentrations of 20 and 40mM) increased the positivity of the serosal side, indicating the presence of Na+-dependent transporters in the absorption of these substances. L-alanine and fructose did not change the positivity of the serosal side. The pyloric ceca seem to be the main site of nutrient absorption in the digestive tract of H. malabaricus.

scholarly journals Digitonin-permeabilized colonic cell layers. Demonstration of calcium-activated basolateral K+ and Cl- conductances.

1988 ◽  
Vol 92 (3) ◽  
pp. 281-306 ◽  
Author(s):  
D Chang ◽  
D C Dawson
Keyword(s):  
Ion Selectivity ◽  
Basolateral Membrane ◽  
Permeability Barrier ◽  
Buffer System ◽  
Bathing Solution ◽  
Marker Enzyme ◽  
Cell Layers ◽  
Mucosal Side ◽  
Apical Membranes ◽  
Conductive Properties

Sheets of isolated turtle colon were exposed to digitonin on the mucosal side to chemically remove the apical membrane as a permeability barrier. Increases in the mucosal uptake of 86Rb, [3H]mannitol, and 45Ca-EGTA, and the appearance of the cytosolic marker enzyme lactate dehydrogenase in the mucosal bath confirmed the permeabilizing effect of the detergent. Basolateral K+ and Cl- currents were generated by imposing transmural ion gradients, and cytosolic free Ca2+ was manipulated by means of a Ca2+-EGTA buffer system in the mucosal bathing solution. Raising the cytosolic free Ca2+ concentration from the nanomolar to the micromolar range activated basolateral conductances for K+ and Cl-. Differences in ion selectivity, blocker specificity, calcium activation kinetics, and divalent cation activation selectivity indicated that the Ca2+-induced increases in the K+ and Cl- conductances were due to separate populations of channels. The results are consistent with the notion that the apical membranes of turtle colon epithelial cells can be functionally removed under conditions that preserve some of the conductive properties of the basolateral membrane, specifically Ca2+-activated conductive pathways for K+ and Cl-. This permeabilized preparation should offer a means for the identification of macroscopic currents that are due to presumed Ca2+-activated channels, and may also provide a model system for the functional reconstitution of channel regulatory mechanisms.

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