Effect of polycations on barrier and transport properties of alveolar epithelium in situ
| Autor: | P. Soler, G. Martet, Georges Saumon |
|---|---|
| Rok vydání: | 1995 |
| Předmět: |
Pulmonary and Respiratory Medicine
Ruthenium red Potassium Channels Physiology Alveolar Epithelium Wasp Venoms In Vitro Techniques Epithelium Permeability Absorption chemistry.chemical_compound Cations Physiology (medical) Cyclic AMP Animals Mannitol Channel blocker Rats Wistar Tetraethylammonium biology Chemistry Sodium Biological Transport Epithelial Cells Cell Biology Adrenergic beta-Agonists Fluid transport Protamine Body Fluids Rats Pulmonary Alveoli Biochemistry Paracellular transport Mastoparan biology.protein Biophysics Intercellular Signaling Peptides and Proteins Peptides |
| Zdroj: | American Journal of Physiology-Lung Cellular and Molecular Physiology. 269:L185-L194 |
| ISSN: | 1522-1504 1040-0605 |
| DOI: | 10.1152/ajplung.1995.269.2.l185 |
| Popis: | We examined the effect of polycations, classes of which are released by activated leukocytes, on the transport properties of the alveolar epithelium in isolated-perfused rat lungs. Protamine, polylysines, and ruthenium red produced rapid, dose-dependent increases in mannitol permeability (PAmann) when instilled into airspaces. The coupling between active transepithelial Na+ transport and alveolar fluid absorption was not altered, despite > 10-fold increases in PAmann. The increase in albumin permeability compared with that in mannitol suggested preservation of alveolar barrier-size selectivity. Tracheal instillation of protamine produced no cellular abnormality, whereas its addition to the perfusate resulted in damage to endothelial and type I cells. Protamine produced an even larger (P < 0.05) increase in PAmann in the presence of isoproterenol or dibutyryl adenosine 3',5'-cyclic monophosphate + 3-isobutyl-1-methyl-xanthine. The stimulation of Na+ and fluid transport by these agents was unaffected by protamine. Mastoparan, a peptide that activates G proteins, produced effects comparable to those of the polycations. The protamine- and mastoparan-induced increase in PAmann was abolished by barium, a K+ channel blocker, but not by zinc, a membrane-protective cation. Other K+ channel blockers, tetraethylammonium and quinine, had no effect. Thus short-term apical application of polycations and mastoparan alter alveolar epithelium paracellular permeability by a noncytotoxic mechanism that is inhibited by barium. The resulting increase in paracellular permeability does not alter fluid absorption driven by active Na+ transport. Polycations have very different effects, depending on whether they are present on one side or the other side of the alveolar capillary barrier. |
| Databáze: | OpenAIRE |
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