REGULATION OF EXTRACELLULAR TRANSEPITHELIAL TRANSPORT
(1977)
Abstract :
Recent information has established that salt, water, and small organic molecules can cross epithelia without traversing cell membranes, that this passage is rate-limited by membrane contacts or "tight" junctions between adjacent cells, and that this passive permeability is adjusted by the magnitude, direction and the solute employed in establishing a transepithelial osmotic gradient. Much of this information has been derived from studies of the toad urinary bladder, a functional analog of the distal mammalian nephron. It is proposed that, with an extension of electrophysiologic and electron microscopic techniques that are available for examination of epithelia, a quantitative analysis of the functional significance of extracellular transport will be carried out. Specifically, attention will be directed to the means by which the electrical conductance of this permeation pathway is adjusted. The principal methods to be employed are those of membrane electrophysiology and transmission electron microscopy with serial analysis of individual preparations during and after exposure to variously created osmotic gradients. Correlation of measurements of short-circuit current and transmural conductance with a quantitative description of the osmotically-induced conformational changes in the structure of cell junctions will be used to evaluate the characteristics of the extracellular pathway in terms of its solute specificity, its importance in passive ion transfer, and its influence on the active transport of sodium by this epithelium. BIBLIOGRAPHIC REFERENCES: Ruocco, N. and D. R. DiBona: Series barrier analysis of limiting junctions in toad urinary bladder. 15th Ann. Meet. Am. Soc. Cell Biol. A748. J. Cell Biol. 67: 374a, 1975.
| Project Number : | 5R01AM017372-03 |
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| ICD : | NAT INST OF ARTHRITIS, DIABETES, DIGESTIVE & KIDNEY DISEASES |
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| IRG : | PHY |
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| Project Terms : | BIOLOGICAL TRANSPORT, ION EXCHANGE AND TRANSPORT, BIOLOGICAL TRANSPORT, MEMBRANE PERMEABILITY AND TRANSPORT, PHYSIOLOGY STUDY SECTION, TISSUE, EPITHELIUM BIOLOGICAL TRANSPORT, ACTIVE TRANSPORT, ION PUMPS, SODIUM PUMP OPTICS, MICROSCOPY, ELECTRON*, electrophysiology |
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REGULATION OF EXTRACELLULAR TRANSEPITHELIAL TRANSPORT
(1977)
Abstract :
The objective of the proposed research is a better understanding of the mechanisms employed in the regulation of extracellular transepithelial transport. Recent information has established that salt, water, and small organic molecules can cross epithelia without traversing cell membranes, that this passage is rate-limited by membrane contacts or "tight" junctions between adjacent cells, and that this passive permeability is adjusted by the magnitude, direction and the solute employed in establishing a transepithelial osmotic gradient. Much of this information has been derived from studies of the toad urinary bladder, a functional analog of the distal mammalian nephron. It is proposed that, with an extension of electrophysiologic and electron microscopic techniques that are available for examination of epithelia, a quantitative analysis of the functional significance of extracellular transport will be carried out. Specifically, attention will be directed to the means by which the electrical conductance of this permeation pathway is adjusted. The principal methods to be employed are those of membrane electrophysiology and transmission electron microscopy with serial analysis of individual preparations during and after exposure to variously created osmotic gradients. Correlation of measurements of short-circuit current and transmural conductance with a quantitative description of the osmotically-induced conformational changes in the structure of cell junctions will be used to evaluate the characteristics of the extracellular pathway in terms of its solute specificity, its importance in passive ion transfer, and its influence on the active transport of sodium by this epithelium.
| Project Number : | 1R01AM017372-01 |
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| ICD : | NAT INST OF ARTHRITIS, DIABETES, DIGESTIVE & KIDNEY DISEASES |
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| IRG : | PHY |
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| Project Terms : | BIOLOGICAL TRANSPORT, MEMBRANE PERMEABILITY AND TRANSPORT, PHYSIOLOGY STUDY SECTION, TISSUE, EPITHELIUM BIOLOGICAL TRANSPORT, ACTIVE TRANSPORT, BODY FLUID BALANCE, ION EXCHANGE AND TRANSPORT, biological transport, sodium OPTICS, MICROSCOPY, ELECTRON*, electrophysiology |
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REGULATION OF EXTRACELLULAR TRANSEPITHELIAL TRANSPORT
(1977)
Abstract :
Recent information has established that salt, water, and small organic molecules can cross epithelia without traversing cell membranes, that this passage is rate-limited by membrane contacts or "tight" junctions between adjacent cells, and that this passive permeability is adjusted by the magnitude, direction and the solute employed in establishing a transepithelial osmotic gradient. Much of this information has been derived from studies of the toad urinary bladder, a functional analog of the distal mammalian nephron. It is proposed that, with an extension of electrophysiologic and electron microscopic techniques that are available for examination of epithelia, a quantitative analysis of the functional significance of extracellular transport will be carried out. Specifically, attention will be directed to the means by which the electrical conductance of this permeation pathway is adjusted. The principal methods to be employed are those of membrane electrophysiology and transmission electron microscopy with serial analysis of individual preparations during and after exposure to variously created osmotic gradients. Correlation of measurements of short-circuit current and transmural conductance with a quantitative description of the osmotically-induced conformational changes in the structure of cell junctions will be used to evaluate the characteristics of the extracellular pathway in terms of its solute specificity, its importance in passive ion transfer, and its influence on the active transport of sodium by this epithelium.
| Project Number : | 5R01AM017372-02 |
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| ICD : | NAT INST OF ARTHRITIS, DIABETES, DIGESTIVE & KIDNEY DISEASES |
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| IRG : | PHY |
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| Project Terms : | BIOLOGICAL TRANSPORT, MEMBRANE PERMEABILITY AND TRANSPORT, PHYSIOLOGY STUDY SECTION, TISSUE, EPITHELIUM BIOLOGICAL TRANSPORT, ACTIVE TRANSPORT, BIOLOGICAL TRANSPORT, ACTIVE TRANSPORT, ION PUMPS, SODIUM PUMP, BIOLOGICAL TRANSPORT, ION EXCHANGE AND TRANSPORT, sodium OPTICS, MICROSCOPY, ELECTRON*, electrophysiology |
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