Redistribution of Gas in XXXX salivary glands following b-adrenergic stimulation.

@entity1169 @entity4856 @entity19 @entity1920 @entity1919 @entity12565 @entity3044 @entity1604
OBJECTIVE: Signalling via b-adrenergic receptors activates heterotrimeric G-proteins, which dissociate into a and by subunits. In salivary glands, the a subunit of Gs stimulates @entity1920 cyclase, increasing @entity1919 levels and promoting exocytosis. The goals of this study were to determine Gas localization in salivary glands and whether it undergoes redistribution upon activation. METHODS: @entity19 parotid and submandibular ( @entity12565 ) glands were fixed with @entity1604 and prepared for immunofluorescence labelling with anti-Gas. RESULTS: In unstimulated parotid and @entity12565 acinar cells, Gas was localized mainly to basolateral membranes. Some parotid acinar cells also exhibited cytoplasmic fluorescence. @entity3044 ( @entity4856 ) stimulation resulted in decreased membrane fluorescence and increased cytoplasmic fluorescence, which appeared relatively uniform by 30 min. Beginning about 2 h after @entity4856 , cytoplasmic fluorescence decreased and membrane fluorescence increased, approaching unstimulated levels in @entity12565 acini by 4 h. Some parotid acini exhibited cytoplasmic fluorescence up to 8 h after @entity4856 . The @entity4856 -induced redistribution of Gas was prevented ( @entity12565 ) or reduced (parotid) by prior injection of @entity1169 . Striated duct cells of unstimulated @entity19 exhibited general cytoplasmic fluorescence, which was unchanged after @entity4856 . CONCLUSIONS: Gas is localized to basolateral membranes of unstimulated salivary acinar cells. Activation of Gas causes its release from the cell membrane and movement into the cytoplasm. Reassociation of Gas with the membrane begins about 2 h after stimulation in the @entity12565 , but complete reassociation takes several hours in the parotid gland. The presence of Gas in striated duct cells suggests a role in signal transduction of secretion and/or electrolyte transport processes.
