| Autor: |
Saumon, Georges, Basset, Guy, Bouchonnet, Francine, Crone, Christian |
| Zdroj: |
Pflügers Archiv: European Journal of Physiology; 1987, Vol. 410 Issue 4/5, p464-470, 7p |
| Abstrakt: |
The absorption of fluid (bicarbonate-buffered Ringer with 10 mmol/l glucose) instilled into rat lung is a Na-coupled process that takes place through two apical transport systems: an amiloride-sensitive Na transport and a Na-glucose co-transport [5]. Fluid absorption in isolated, perfused rat lungs and the permeability toH-mannitol of alveolar epithelium were studied in control conditions and during stimulation of the alveolar epithelium by cAMP or isoproterenol. cAMP led to a threefold increase in the rate of fluid absorption and to an increase in the paracellular permeability. A similar response was found following \-adrenergic stimulation obtained with isoproterenol in the perfusate. The increase in fluid transport was due to enhancement of the amiloride-sensitive component of Na transport. The Na-glucose co-transport which accounts for about 60% of fluid absorption in control conditions was depressed, possibly as a consequence of a depolarization of the apical alveolar cell membrane. Fluid absorption was reduced by 40% by apical amiloride (10 mol/l) in control lungs and to an even larger extent in isoproterenol-stimulated lungs; it was completely abolished by amiloride in cAMP stimulated lungs. Since the Na-glucose co-transport was still operative, this suggests that a secretory process was triggered. This was confirmed in experiments in which both kinds of transport were inhibited with a combination of amiloride and glucose-free Ringer. In these conditions fluid balance was zero in unstimulated lungs whilst fluid entry into alveoli was observed in isoproterenol and cAMP stimulated lungs. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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