Opening of tight junctions in frog skin by hypertonic urea solutions
- 76 Downloads
The movements and distribution of lanthanum have been studied in frog skins treated on the outside with Ringer's solution to which 400mm urea had been added. Under these conditions,140La moved across the skin. This finding is in contrast with what is observed in control skins, which are impermeable to lanthanum. Examination with the electron-microscope of skins fixed during equilibration with outside hypertonic solutions plus lanthanum, showed penetration of the tracer from the outside into the intercellular spaces of all the inner layers of the epidermis. The occluding zonules (tight junctions) that normally prevent the inward movement of lanthanum beyond the outer border of the stratum granulosum (SG) are open. As a consequence, most intercellular spaces along the lateral cell surfaces of the SG were permeated by lanthanum throughout their extension. In skins treated with hypertonic solutions and then allowed to recover in normal Ringer's, the occluding zonules of the SG were impermeable to lanthanum, and140La did not move across the epidermis. These observations show that the increased skin permeability caused by outside hypertonic solutions results mainly from a reversible opening of tight junctions.
KeywordsUrea Lanthanum Tight Junction Intercellular Space Lateral Cell
Unable to display preview. Download preview PDF.
- Martínez-Palomo, A. 1971. Intercellular junctions in normal and in malignant cells.In: Pathobiology Annual 1971. H. L. Ioachim, editor, p. 261. Appleton-Century-Crofts, New York.Google Scholar
- Moeller, Th. 1963. The Chemistry of the Lanthanides. Reinhold Publishing Co. New York, p. 117.Google Scholar
- Sillen, L. G., Martell, A. E. 1964. Stability Constants of Metal-Ion Complexes. The Chemical Society. Burlington House, London.Google Scholar
- Ussing, H. H. 1969. The interpretation of tracer fluxes in terms of membrane structure.Quart. Rev. Biophys. 1:365.Google Scholar
- Ussing, H. H. 1971. Introductory remarks.Phil. Trans. 262:85.Google Scholar
- Ussing, H. H., Andersen, B. 1956. The relation between solvent drag and active transport of ions.Proc. 3rd Int. Cong. Biochem., Brussels pp. 434–440. Academic Press Inc., New York.Google Scholar