Cl Secretagogues Reduce Basolateral K Permeability in the Rabbit Corneal Epithelium
| Autor: | A. C. Zamudio, Oscar A. Candia |
|---|---|
| Rok vydání: | 2002 |
| Předmět: |
Male
medicine.medical_specialty Epinephrine Physiology Biophysics Biological Transport Active In Vitro Techniques Basement Membrane Permeability Membrane Potentials chemistry.chemical_compound Internal medicine medicine Animals Secretion Ouabain Transepithelial potential difference Epithelial polarity Corneal epithelium Forskolin Chemistry Colforsin Sodium Electric Conductivity Epithelium Corneal Isoproterenol Depolarization Cell Biology Apical membrane Rubidium Electrophysiology medicine.anatomical_structure Endocrinology Permeability (electromagnetism) Potassium Female Rabbits Chlorine Microelectrodes |
| Zdroj: | Journal of Membrane Biology. 190:197-205 |
| ISSN: | 1432-1424 0022-2631 |
| Popis: | The stromal-to-tear transport of Cl by the rabbit corneal epithelium is increased by pharmacological effectors (secretagogues) that raise cAMP. It is well established that such secretagogues increase the apical membrane permeability to Cl and thus facilitate the efflux of the anion. However, we and others have found that cAMP-elevating agents frequently decrease the transepithelial potential difference across the rabbit cornea. The mechanism underlying this latter phenomenon had not been characterized. In this report, transepithelial and microelectrode studies were combined with measurements of unidirectional fluxes of 36Cl, 22Na and 86Rb to show that secretagogues known to act via cAMP also decrease the K permeability of the basolateral membrane, which by cellular depolarization would decrease apical Cl secretion. This effect was increasingly pronounced as a function of concentration when agents (e.g., epinephrine, isoproterenol) were applied to the apical side of the preparations. The addition of these agonists to the basolateral bathing solution, or of forskolin to the apical side, solely elicited inhibitions of basolateral K permeability. It seems that apical Cl and basolateral K conductances are independently and inversely regulated by cAMP. The opposite effects that cAMP could have on fluid secretion and epithelial thickness, by increasing apical Cl permeability but decreasing basolateral K permeability, may serve as a mechanism to maintain epithelial thickness within a narrow range. |
| Databáze: | OpenAIRE |
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