Molecular mechanisms of calcium-evoked chloride and bicarbonate secretion from murine airway submucosal gland serous acinar cells.

Format:

Book

Thesis/Dissertation

Author/Creator:

Lee, Robert J.

Contributor:

Foskett, J. Kevin, advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Physiology.

Cytology.

0379.

0433.

0719.

Penn dissertations--Cell and molecular biology.

Cell and molecular biology--Penn dissertations.

Local Subjects:

Penn dissertations--Cell and molecular biology.

Cell and molecular biology--Penn dissertations.

0379.

0433.

0719.

Physical Description:

219 pages

Contained In:

Dissertation Abstracts International 70-01B.

System Details:

Mode of access: World Wide Web.

text file

Summary:

Airway submucosal gland serous acinar cells are crucial to the secretion of airway surface liquid in cartilaginous airways. However, the molecular mechanisms of serous cell ion and fluid transport have been poorly characterized. To address this, primary serous acinar cells were isolated from the mouse airway and identified by immunofluorescence microscopy and gene expression profiling. Physiological mechanisms of serous cell ion transport were studied using differential interference contrast microscopy of cell volume to track agonist induced changes in cell solute content combined with simultaneous quantitative fluorescence microscopy of ion indicator dyes to measure the intracellular concentrations of ions involved in driving fluid secretion (Cl -, HCO3-) and regulating it (Ca2+ ). Stimulation of serous cells with the cholinergic agonist carbachol caused a profound increase in intracellular Ca2+ concentration ([Ca2+]i) that led to a ∼20% decrease in cell volume. This resulted from a loss of >60% of cellular KCl content and osmotically obliged water, likely reflecting activation of Cl-/fluid secretion due to Ca2+-activation of plasma membrane K+ and/or Cl- permeabilities. Cl- secretion was sustained by the activity of the basolaterally-localized Na+ K+ 2Cl- cotransporter NKCC1, leading to solute uptake and cell swelling upon removal of agonist, lowering of [Ca2+ ]i, and deactivation of Ca2+-activated membrane permeabilities. A profound cytoplasmic acidification accompanied Ca 2+-activated cell shrinkage, indicative of HCO3 - secretion, followed by an alkalinization mediated by activity of the basolaterally localized Na+/H+ exchanger NHE1, likely a mechanism to sustain HCO3- secretion. The ratio and identical pharmacological sensitivities of agonist-evoked Cl - and HCO3- effluxes suggested they occur through the same pathway, likely a Ca2+-activated secretory Cl- channel. Despite expression of the apically-localized cystic fibrosis transmembrane conductance regulator (CFTR) anion channel in these cells, CFTR appeared to play no significant role in either Ca2+-stimulated Cl- or HCO3- secretion. These data suggest that serous cells secrete Cl- and HCO3 - -rich fluid in response to Ca2+-mobilizing agonists and contribute to the understanding of Cl-, HCO3 -, and fluid secretion in the airway.

Notes:

Thesis (Ph.D. in Cell and Molecular Biology) -- University of Pennsylvania, 2008.

Source: Dissertation Abstracts International, Volume: 70-01, Section: B, page: 0138.

Adviser: J. Kevin Foskett.

Local Notes:

School code: 0175.

ISBN:

9781109008234

Access Restriction:

Restricted for use by site license.