The long-term, overall objective of this project is to elucidate the mechanisms underlying the secretion of saliva and of its two major fractions, the water/electrolyte and macromolecular fractions. The more immediate goal of the studies described in this proposal is to characterize the ion transport systems which are involved in the formation of the fluid/electrolyte fraction of primary or precursor saliva by acinar cells. The proposed studies are based on previous evidence indicating that salivary fluid originates primarily in these cells and that its secretion is inhibited by ouabain and by furosemide. A model of the ionic mechanism of salivary fluid secretion is proposed, involving, as a first step, a Na-coupled, furosemide-sensitive Cl-entry into the cells, which is driven by the Na gradient generated by an ouabain-sensitive Na, K pump. We propose to use, therefore, dispersed acini isolated from the rat submandibular gland to investigate the presence and activation of these two transport systems.
The specific aims are to measure: 1) furosemide-sensitive fluxes of Na-22 and Cl-36. Both isotope exchange and net fluxes will be measured before and after exposure to cholinergic and adrenergic agents. The effects of ouabain, of changes in the ionic composition (Na, C1, K, Ca) of the incubation medium, of the Ca++ ionophore A23187, of exogenous derivatives of cAMP and cGMP and of substances which alter cell nucleotide content (such as forskolin and Na nitroprusside) will also be investigated. 2) The rate of binding of H-3 ouabain. The time required for half maximal and maximal binding, association, dissociation and equilibrium dissociation (KD) constants and density of binding sites (Bmax) will be measured under the same experimental conditions indicated for isotope fluxes. 3) Ouabain-sensitive Rb-86 uptake. Rates of uptake will be measured in the same experimental conditions as H-3-ouabain binding. The results of these studies should provide more direct evidence for the presence and activation of two ion transport systems involved in the secretion of fluid and electrolytes by salivary acinar cells and contribute to our understanding of the mechanisms of saliva formation.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
Research Project (R01)
Project #
5R01DE009270-06
Application #
3223084
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Project Start
1989-07-01
Project End
1993-06-30
Budget Start
1991-07-01
Budget End
1992-06-30
Support Year
6
Fiscal Year
1991
Total Cost
Indirect Cost
Name
Lovelace Respiratory Research Institute
Department
Type
DUNS #
City
Albuquerque
State
NM
Country
United States
Zip Code
87108
Castro, R; Sun, X H; Liu, X-B et al. (2008) Inhibition of Ca2+ influx by surfactant in NR8383 alveolar macrophages. Inflamm Res 57:489-96
Sun, X; Liu, X B; Martinez, J R et al. (2001) Effects of radiation on Ca2+ signaling in salivary epithelial cell lines transfected with Bcl-2 and Bcl-XL. Eur J Oral Sci 109:103-8
Liu, X; Mork, A C; Sun, X et al. (2001) Regulation of Ca(2+) signals in a parotid cell line Par-C5. Arch Oral Biol 46:1141-9
Mork, A C; Sun, X; Liu, X et al. (2000) Regulation of (1-3)-beta-glucan-stimulated Ca(2+) influx by protein kinase C in NR8383 alveolar macrophages. J Cell Biochem 78:131-40
Liu, X B; Sun, X; Mork, A C et al. (2000) Characterization of the calcium signaling system in the submandibular cell line SMG-C6. Proc Soc Exp Biol Med 225:211-20
Sun, X; Liu, X B; Martinez, J R et al. (2000) Effects of low concentrations of paraoxon on Ca(2+) mobilization in a human parotid salivary cell-line HSY. Arch Oral Biol 45:621-38
Sun, X; Martinez, J R; Zhang, G H (1999) Inhibition of Ca2+ influx by pentoxifylline in NR8383 alveolar macrophages. Immunopharmacology 43:47-58
Sugita, K; Mork, A C; Zhang, G H et al. (1999) Modulation of Ca2+ mobilization by protein kinase C in the submandibular duct cell line A253. Mol Cell Biochem 198:39-46
Zhang, G H; Martinez, J R (1999) Effects of forksolin, dibutyryl cAMP and H89 on Ca2+ mobilization in submandibular salivary cells of newborn rats. Arch Oral Biol 44:735-44
Mork, A C; Zhang, G H; Martinez, J R (1999) Modulation of Ca2+ mobilization by protein kinase C in rat submandibular acinar cells. J Cell Biochem 72:47-55

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