Studies on transmural potentials in vitro in relation to intestinal absorption VI. The effect of sugars on electrical potential profiles in jejunum and ileum

Lyon, I.; Sheerin, Harland E.

doi:10.1016/0005-2736(71)90078-2

Cited by 31 publications

(15 citation statements)

References 18 publications

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“…In these experiments the transfer potential in the rat small intestine is seen to be entirely due to an increase in the serosal potential, the mucosal potential remaining unchanged. This is in agreement with the recent results of Lyon & Sheerin (1971) also in the rat, Gilles-Baillien & Schoffeniels (1965) in the tortoise and Wright (1966) in the hamster. These observations are consistent with the concept of a serosally located, electrogenic sodium pump, which is stimulated by the presence of actively transported sugars and amino acids (Schultz & Zalusky, 1964b, 1965Crane, 1965).…”

Section: Discussionsupporting

confidence: 94%

“…These membrane potentials together with the transmural R. J. C. BARRY AND JACQUELINE EGGENTON potential difference can be measured using a micro-electrode technique. A number of previous workers have made such investigations in tortoise (Gilles-Baillien & Schoffeniels, 1965;Wright, 1966), bullfrog (White & Armstrong, 1970, hamster (Wright, 1966), rabbit (Rose & Schultz, 1970, 1971a and most recently rat (Lyon & Sheerin, 1971). The changes in transmural potential difference obtained under different experimental conditions are reflected in changes in membrane potentials.…”

Section: Introductionmentioning

confidence: 98%

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Membrane potentials of epithelial cells in rat small intestine

Barry¹,

Eggenton²

1972

The Journal of Physiology

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1. Stripped sacs of rat jejunum in which the outer muscle layers had been removed were found to maintain substantial transport and electrical activities. 2. Mucosal and serosal membrane potentials of epithelial cells of normal and stripped everted sacs of rat jejunum were recorded in vitro together with the transmural potential difference. 3. The cell interior was negative relative to both serosal and mucosal fluids, the transmural potential being the sum of the two membrane potentials. 4. Changes in the transmural potentials in the presence of actively transferred hexoses and amino acids were entirely due to variations in the serosal potential, the mucosal potential being unchanged. 5. Serosal and transmural potential increases on the addition of galactose were consistent with Michaelis—Menten kinetics, giving apparent Km values of 14·9 and 14·1 m M respectively. 6. Phlorrhizin, ouabain, 2,4‐dinitrophenol and sodium fluoroacetate inhibited serosal potential changes in the presence of galactose. 7. Osmotic potentials resulting from transmural osmotic gradients originated from the serosal layers of the tissue. 8. The results are consistent with the concept of a serosally located, electrogenic sodium pump which is stimulated by actively transferred hexoses and amino acids. The sodium‐dependent entry mechanism at the mucosal membrane is non‐electrogenic.

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Section: Discussionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 98%

Membrane potentials of epithelial cells in rat small intestine

Barry¹,

Eggenton²

1972

The Journal of Physiology

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“…In conditions similar to those used in our experiments, it has been reported that the PD at the luminal membrane of rat intestinal epithelial cells is approximately 10 mV, cell interior negative, and that the PD at the abluminal side of the cell is approximately 12 mV, cell interior negative [1,15]. It will be noted that the PD at the luminal membrane does not have the appropriate polarity for the observed directions of weak electrolyte transport, but the PD at the abluminal membrane does have an appropriate orientation.…”

Section: Three-compartment System For Weak Electrolyte Transportsupporting

confidence: 55%

“…The transmural PD of rat intestine can be represented as the sum of two components in series [1,15]. These component PD's are usually considered to be associated with the luminal and abluminal membrane complexes of the epithelial cells, and Eq.…”

Section: Three-compartment System For Weak Electrolyte Transportmentioning

confidence: 99%

Intestinal Transport of Weak Electrolytes

Jackson

Shiau

Bane

et al. 1974

The Journal of General Physiology

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A study has been made of the transmural fluxes of benzoic, phenylacetic, and pentanoic acids, benzylamine, hexylamine, and D-amphetamine across rat jejunum incubated in vitro. The M to S fluxes of the weak acids were greater than their corresponding S to M fluxes, and the S to M fluxes of the weak bases were larger than their M to S fluxes. These patterns of asymmetric movements were observed when the transmural electrical potential difference was clamped at 0 mV, and when the pH values of the mucosal and serosal fluids were identical. The effects of a weak acid on the fluxes of other weak electrolytes were qualitatively similar when the effector weak acid was added to the mucosal fluid, and when it was added to the serosal fluid. But the effects of a weak base on the fluxes of other weak electrolytes were dependent upon its location, and the interactions observed when the effector weak base was added to the mucosal fluid were qualitatively different than those seen when it was added to the serosal fluid. The interactions between weak electrolytes could readily be explained in terms of the function of a system of three compartments in series, in which the pH of the intermediate compartment is greater than that of the bulk phases. But these observations could not be explained in terms of an analogous system involving an intermediate compartment of low pH, or in terms of a carrier mediated system. The transport function of the three-compartment system can be described in the form of an equation, and it is found that a pH difference of less than 0.5 unit may explain our observations on weak electrolyte transport.The mechanisms involved in the intestinal transport of weak electrolytes have been the subject of several previous investigations. Some studies have demon-

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“…This suggests that the mechanism of the genesis of the sugar-evoked potential is entirely different from that of the osmotic potential change and the participation of the osmotic potential is negligibly small in the formation of the sugarevoked potential. As to the site of generation of the sugar-evoked potentials, HOSHI and KOMATSU (1970), ROSE and SCHULTZ (1971) and WHITE and ARMSTRO (1971) demonstrated evidence showing that the site is the brush border membrane of cells, while GILLES-BAILLIEN and SCHOFFENIELS (1965), WRIGHT (1966), LYO andSHEERIN (1971) andEGGENTON (1972) proposed that an electrogenic sodium pump located at the serosal membrane might be stimulated by increased sodium entry coupled with sugar molecules. Thus, there are still controversial views on this problem, but all investigators think the mucosal or serosal membrane of cells as the site of generation.…”

Section: Discussionmentioning

confidence: 99%

Effects of Mucosal Hyperosmolarity on Active Sugar Transport and the Sugar-Evoked Potential in Isolated Small Intestine of the Toad

Saito

Hoshi

1973

Jpn.J.Physiol

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Summary Isolated small intestines of toads were mounted in a flux chamber or suspended from a cannula as an everted sac, and osmolarity of solutions bathing the mucosal surface was changed by adding Dmannitol or polyethylene glycol to the standard solution. With increase in osmolarity we observed increases in (1) resistance of transmural water flow, (2) transmural electrical resistance, (3) tissue electrolyte content, (4) a decrease in water content of the tissue, (5) a change in transmural potential difference in the direction that the mucosal side becomes more positive, and (6) a reduction in size of the glucose-evoked potential. On the other hand the tissue uptake of D-glucose and Dgalactose from the mucosal solution did not significantly change with the treatment. Within a range of osmolarity change (less than 200 mOsm/ liter), results (3) and (4) can be interpreted as due to a mere withdrawal of water from the tissue. The relationship between the size of the osmotic potential change and the osmolarity difference was similar to that between the rate of net water flow and the osmolarity difference. The fact that mucosal hyperosmolarity exerts strong influence on the sugarevoked potential but no significant influence on the uptake of sugar is interpreted as the effect of the hyperosmolarity being a consequence of changes in electrical resistance representing the lateral intercellular space.An elevation or a reduction of osmolarity of the solution bathing the mucosal surface of the small intestine is known to cause changes in passive permeability to water and organic solutes and in the transmural potential of the tissue. LOES-CHKE et al. (1970 have shown that osmotic water flow permeability and passive permeability to sugar molecules measured in the presence of phlorizin are distinctly higher in the presence of mucosal to serosal water flow than in the presence of water flow in the reverse direction. They ascribed such observed asymmetry to different structural changes which were induced concomitantly by osmotic gradients with different directions. SMYTH and WRIGHT (1966) showed that the transmural potential difference of the small intestine was altered by changing osmolarity of the mucosal solution, and LOESCHKE et al. (1971) showed that the magnitude of such osmotic potential changes were also asymmetrical depending on the direction of elicited water flow. Similar asymmetrical permeability characteristics and the relation of them to structural changes in the epithelial cells induced by osmotic water flow have extensively been studied in the gall bladder (TORME and DIAMOND, 1967;SMULDERS et al., 1972;WRIGHT et al., 1972). The effect of transmural osmotic gradients on the active transport of nonelectrolytes by the small intestine has not been studied extensively. PARSO and WINGATE (1961) found that changes in osmolarity of the mucosal solution by changing sodium concentration had little effect on glucose transport in rat small intestine. However, DINDA et al. (1972) observed in hamster intestine a unique eff...

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Studies on transmural potentials in vitro in relation to intestinal absorption VI. The effect of sugars on electrical potential profiles in jejunum and ileum

Cited by 31 publications

References 18 publications

Membrane potentials of epithelial cells in rat small intestine

Membrane potentials of epithelial cells in rat small intestine

Intestinal Transport of Weak Electrolytes

Effects of Mucosal Hyperosmolarity on Active Sugar Transport and the Sugar-Evoked Potential in Isolated Small Intestine of the Toad

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