Document Detail


The Na+/H+ antiporter in rat alveolar type II cells and its role in stimulated surfactant secretion.
MedLine Citation:
PMID:  2833308     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
We used the pH-sensitive fluorescent probe 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein (BCECF) to identify Na+/H+ exchange in freshly isolated rat alveolar type II cells and alveolar type II cells in primary culture. The intracellular pH (pHi) of freshly isolated alveolar type II cells was 7.36 +/- 0.05 (n = 3). When freshly isolated alveolar type II cells were acid loaded with nigericin in sodium-free buffer, the pHi dropped to 6.59 +/- 0.04 and remained low in sodium-free buffer. When acid-loaded cells were subsequently incubated with NaCl, pHi increased in a dose-dependent manner. Amiloride (0.1 mM) inhibited the sodium-induced increase in pHi. When the acid-loaded cells were resuspended in an unbuffered choline chloride solution, the cells secreted H+ in a sodium-dependent and amiloride-inhibitable manner. Alveolar type II cell monolayers, which were cultured for 22 h on glass coverslips and then loaded with BCECF, had a resting pHi of 7.48 +/- 0.05 (n = 4). Nigericin acidified these cultured cells in the absence of sodium and NaCl increased the pHi of these acid loaded cells as observed in freshly isolated cells. Secretagogues of pulmonary surfactant, 12-O-tetradecanoylphorbol 13-acetate (TPA) and terbutaline, did not change pHi. Inhibition of the Na+/H+ antiporter by the addition of amiloride to a Na+ containing medium or the substitution of choline for Na+ did not inhibit stimulated phosphatidylcholine secretion. We conclude that pHi regulation in rat alveolar type II cells is in part mediated by an amiloride-sensitive Na+/H+ antiporter, but this system appears not to be involved in TPA- or terbutaline-induced pulmonary surfactant secretion in primary culture.
Authors:
K Sano; G R Cott; D R Voelker; R J Mason
Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Biochimica et biophysica acta     Volume:  939     ISSN:  0006-3002     ISO Abbreviation:  Biochim. Biophys. Acta     Publication Date:  1988 Apr 
Date Detail:
Created Date:  1988-05-26     Completed Date:  1988-05-26     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  0217513     Medline TA:  Biochim Biophys Acta     Country:  NETHERLANDS    
Other Details:
Languages:  eng     Pagination:  449-58     Citation Subset:  IM    
Affiliation:
Department of Medicine, National Jewish Center for Immunology and Respiratory Medicine, Denver, CO 80206.
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MeSH Terms
Descriptor/Qualifier:
Amiloride / pharmacology
Animals
Carrier Proteins / metabolism*
Fluoresceins
Fluorescent Dyes
Hydrogen-Ion Concentration
Kinetics
Lung / cytology,  drug effects,  metabolism*
Nigericin / pharmacology
Pulmonary Surfactants / secretion*
Rats
Rats, Inbred Strains
Sodium Chloride / pharmacology
Sodium-Hydrogen Antiporter
Terbutaline / pharmacology
Tetradecanoylphorbol Acetate / pharmacology
Grant Support
ID/Acronym/Agency:
HL-01354/HL/NHLBI NIH HHS; HL-29891/HL/NHLBI NIH HHS
Chemical
Reg. No./Substance:
0/Carrier Proteins; 0/Fluoresceins; 0/Fluorescent Dyes; 0/Pulmonary Surfactants; 0/Sodium-Hydrogen Antiporter; 16561-29-8/Tetradecanoylphorbol Acetate; 23031-25-6/Terbutaline; 2609-46-3/Amiloride; 28380-24-7/Nigericin; 7647-14-5/Sodium Chloride; 85138-49-4/2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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