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The effects of P O2 upon transepithelial ion transport in fetal rat distal lung epithelial cells
Author(s) -
Ramminger S. J.,
Baines D. L.,
Olver R. E.,
Wilson S. M.
Publication year - 2000
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.2000.t01-1-00539.x
Subject(s) - ion transporter , fetus , lung , chemistry , epithelium , biophysics , microbiology and biotechnology , anatomy , biology , ion , medicine , pathology , pregnancy , organic chemistry , genetics
1 Isolated rat fetal distal lung epithelial (FDLE) cells were cultured (for 48 h) at P O2 levels between 23 and 142 mmHg. Higher P O2 levels between 23 and 142 mmHg. Higher P O2 was associated with increased short circuit current ( I SC ) and increased abundance of the Na + channel protein α‐ENaC. P O2 had no effect upon I SC remaining after apical application of amiloride (10 μM). 2 Studies of cells maintained (for 48 h) at P O2 levels of 23 mmHg or 100 mmHg, and subsequently nystatin permeabilized (50 μM), showed that high P O2 increased Na + pump capacity. This response was apparent 24 h after P O2 was raised whilst it took 48 h for the rise in I SC seen in intact cells to become fully established. Both parameters were unaffected by raising P O2 for only 30 min. 3 Basolateral application of isoprenaline (10 μM) did not affect I SC in cells maintained at 23 mmHg but evoked progressively larger responses at higher P O2 . The response seen at 142 mmHg was larger than at 100 mmHg, the normal physiological alveolar P O2 . 4 Isoprenaline had no effect on Na + pump capacity at P O2 levels of 23 mmHg or 100 mmHg, but stimulated Na + extrusion at 142 mmHg. Increasing P O2 above normal physiological levels thus allows the Na + pump to be controlled by isoprenaline. This may explain the enhanced sensitivity to isoprenaline seen under these slightly hyperoxic conditions. 5 Changes in P O2 mimicking those occurring at birth thus exert profound influence over Na + transport in FDLE cells and the Na + pump could be an important locus at which this control is exercised.