Transport Pathways in Biological Membranes

Ussing, Hans H.; Erlij, David; Lassen, Ulrik V.

doi:10.1146/annurev.ph.36.030174.000313

Cited by 132 publications

(41 citation statements)

References 73 publications

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“…In "leaky" epithelia, such as that of the small intestine, the proximal kidney tubule, and the gall bladder, where the electric conductance across the intercellular spaces forms around 80-96% of the total transepithelial conductance (10)(11)(12)(13), most of the passive ion transport across the epithelium occurs through the intercellular spaces (10,(14)(15)(16)(17)(18)(19). Water flows into these Response of the Intestine to Hypertonic Solutions during Maturation spaces in response to a local osmotic gradient produced by active or passive solute transport into these spaces (10,(14)(15)(16)(17)(18)(19).…”

Section: Discussionmentioning

confidence: 99%

“…Water flows into these Response of the Intestine to Hypertonic Solutions during Maturation spaces in response to a local osmotic gradient produced by active or passive solute transport into these spaces (10,(14)(15)(16)(17)(18)(19). From the mucosal medium, flow of water into the intercellular spaces can be directly through the tight junctions (18) and/or through the cell membranes, and is associated with dilatation of the spaces (20)(21)(22).…”

Section: Discussionmentioning

confidence: 99%

“…The cannulated segments were inserted back into the abdominal cavity and perfused in situ at a rate of 0.2 ml/min, with a solution containing, per liter: 145 mmol sodium chloride, 20 mg phenol red, and mannitol (Fisher Scientific Co., Pittsburgh, Pa. ) in quantities sufficient to achieve osmolalities of 375, 500, and 700 mosmol/kg. In an initial study of' rats at the same age periods, 15-to 20-cm long segments of' the jejunum and ileumi were perfuised with the above solution with enough mannitol to achieve oismolalities of'295-305 mosmol/kg. This solution wats slightly hypotonic compared with rat serum osmolality of'305-309 mosmnol/kg under normal conditions.…”

Section: Methodsmentioning

confidence: 99%

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Maturation of Jejunum and Ileum in Rats

Younoszai¹,

Sapario²,

Laughlin³

1978

J. Clin. Invest.

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A B S T R A C T During osmotic diarrhea, loss of water and electrolytes appears to be greater in infants than in adults. In 2-, 3-, and 7-wk-old rats, we studied net transport of H20, Na, and Cl, during in vivo perfusion of segments of the jejunum and ileum, from solutions with osmolalities of 300, 375, 500, or 700 mosmol/kg. In the jejunal segments, from the hypertonic solutions net transport of H20, Na, and Cl was into the lumen and greater in the 2-than 7-wk-old rats. In the ileal segments, transport of water was into the lumen, transport of Na was minimal and variable, whereas transport of Cl was usually out of the lumen. In 3-wk-old rats, transport rates were intermediate between those in 2-and 7-wk-old rats. The calculated filtration coefficient (microliters of H20 transported per hour per unit osmolality gradient-lumen-serum -per gram dry weight) of water suggested that the resistance to water flow did not increase with rise in luminal hypertonicity in the jejunum of the 2-and 3-wk-old rats, whereas in jejunum of the 7-wk-old rats and in ileum of rats in all three ages, the resistance to water flow increased with the rise in luminal osmolality. The differences in the transport rates and the resistance to water flow, between segments of the 2-, 3-, and 7-wk-old rats, suggested a maturational phenomenon that appears to continue beyond the 3rd wk of life and could have been due to differences in some physical property of the mucosal membrane.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Maturation of Jejunum and Ileum in Rats

Younoszai¹,

Sapario²,

Laughlin³

1978

J. Clin. Invest.

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“…The notion that epithelia can be classed into 'tight', 'intermediate' and 'leaky' ones in terms of their total electrical resistance (Windhager, Boulpaep & Giebisch, 1967;Frdmter, 1972) has gained prominence in recent years (Ussing, Erlij & Lassen, 1974;Erlij, 1976). An important corollary of this notion is that isotonic fluid transport appears to take place only across leaky epithelia (cf.…”

Section: Introductionmentioning

confidence: 99%

The effect of external pH on osmotic permeability, ion and fluid transport across isolated frog skin.

Fischbarg¹,

Whittembury²

1978

The Journal of Physiology

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SUMMARY1. The rate of volume flow across frog skin induced by an osmotic gradient was measured when normal (7.4) and low pH (2-28) solutions bathed the outside. The osmotic permeabilities (Pos) were 2-4 + 0-4 and 4 8 + 1.0 ,um/sec, respectively. The change in Po. induced by low pH was reversible.2. Volume flow in the absence of an osmotic gradient was measured at normal and low pH. Values were 0-69 + 0-13 and 1.1 + 0 2 #tl./hr. cm2, respectively; the paired differences were significant (P < 0.0025). This change in rate was partially reversible upon return to normal pH.3. The potential difference (V) and short-circuit current (1I) across skins were measured under several conditions and the following equivalent parameters in a simplified electrical model were computed: total resistance (Rt); shunt resistance (R8); electromotive force of the pump (ENa); and salt transport at open circuit (JNacl). Representative figures were (a), at pH 7 4: Is = 14 + 1*6,A/cm2; Rt = 3.3+0 4 kW. cm2; R8 = 7-2 + 1c0W.cm2; ENa = 103 + 38 mV; JNaCl =-2 + 1.2 ,A/cm2; (b), at pH2-28: Is = 8-3+2-1itA/cm2; Rt = 046+0121cQ.cm2; Rs= 0-65+0-06 kW.cm2;EN. = 59+25mV;JNacl = 94+33 /%A/cm2. 4. From the electrical parameters measured concomitantly with the rate of fluid transport in given experiments, the expected salt concentration of the transported fluid was 0 30 + 0-08 and 0-38 + 0-08 mole/l. at normal and low pH, respectively, or some 3-4 times hyperosmotic with respect to the medium.5. Treatment with low pH on the outside has been found to open the intercellular junctions in previous studies. The present results suggest that, if such an effect occurs, it is localized only to a small fraction of the cell perimeter. Making certain assumptions that fraction could be as low as 0-003.6. Low pH on the outside reversibly changes the electrical parameters of a 'tight' epithelium like the frog skin into values more typical of 'intermediate' epithelia; both the total and shunt resistances decrease to about 0.1 of their normal values.These changes do not apparently affect the osmolarity of the transported fluid.

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“…DISCUSSION Ussing (1965) suggested that hypo-and hypertonic conditions alter the short-circuit current across frog skin by changing cell volume. It has been shown that changes in sodium and water movement across frog skin are associated with morphological changes of the intercellular spaces (see Ussing, Erlij & Lassen, 1974). However, the mechanism by which variations in cellular volume influence sodium transport is uncertain.…”

Section: Endogenous Prostaglandins In Frog Skin 227mentioning

confidence: 99%

A role for endogenous prostaglandins in the short‐circuit current responses to osmolal changes in isolated frog skin

Hall¹,

O'Regan²,

Quigley³

1977

The Journal of Physiology

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SUMMARY1. Reduction in osmolality of the Ringer solution bathing the morphological inside of frog skin (by lowering the NaCI concentration) caused a significant increase in sodium transport as measured by the short-circuit current. Pretreatment of the skin with acetylsalicylic acid (2.5 x 10-4 M) abolished the short-circuit current and open-circuit potential responses to osmolal change.2. The output of prostaglandin-like material from isolated frog skin was increased by incubating the skin in hypotonic Ringer solution.3. The cyclic AMP levels of isolated frog skin were also increased by a reduction in the osmolality of the Ringer fluid bathing the skin.4. Prostaglandin-like material was released both by the separated epithelial and dermal layers of frog skin and the output from both layers, on a unit wet weight basis, did not differ.5. The output of prostaglandin-like material from the separated layers of the skin was substantially greater than from whole skin. Indomethacin (6 x 10-6 M) reduced the output of this material by more than 90 % from both layers.6. The release of prostaglandin-like material from the separated layers of the skin was not altered by a reduction in osmolality of the bathing medium.7. It is concluded that a reduction in the osmolality of the solution bathing frog skin stimulates prostaglandin production and that the increased level of prostaglandins stimulates transepithelial sodium transport by stimulating cyclic AMP accumulation. It is also concluded that the response to osmolal change can only occur in intact skin since separation of the epithelial and dermal layers abolished the increase in the release of

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Transport Pathways in Biological Membranes

Cited by 132 publications

References 73 publications

Maturation of Jejunum and Ileum in Rats

Maturation of Jejunum and Ileum in Rats

The effect of external pH on osmotic permeability, ion and fluid transport across isolated frog skin.

A role for endogenous prostaglandins in the short‐circuit current responses to osmolal changes in isolated frog skin

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