Stimulation-associated redistribution of Na,K-ATPase in rat lacrimal gland |
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Authors: | Samuel C. Yiu Ross W. Lambert Michael E. Bradley Claire E. Ingham Klane L. Hales Richard L. Wood Austin K. Mircheff |
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Affiliation: | (1) Department of Physiology and Biophysics, University of Southern California, School of Medicine, 90033 Los Angeles, California;(2) Department of Anatomy and Cell Biology, University of Southern California, School of Medicine, 90033 Los Angeles, California |
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Abstract: | Summary To test the possibility that stimulation of secretion leads Na,K-ATPase to be recruited from cytoplasmic pools and inserted into basal-lateral plasma membranes, we surveyed the subcellular distributions of Na, K-ATPase in resting and stimulated fragments of rat exorbital lacrimal gland. After a two-dimensional separation procedure based on differential sedimentation and density gradient centrifugation, we defined sixdensity windows, which differ from one another in their contents of biochemical markers. The membranes equilibrating inwindow I could be identified as a sample of basal-lateral membranes; in resting preparations these membranes contained Na,K-ATPase enriched 16.6-fold with respect to the initial homogenates.Windows II throughVI contained various cytoplasmic membrane populations; these accounted for roughly 80% of the total recovered Na,K-ATPase activity. Thirty-minute stimulation with 10 m carbachol caused a 1.4-fold increase (P<0.05) in the total Na,K-ATPase content ofwindow I; this increase could be largely accounted for by a 1.7-fold decrease in the total Na,K-ATPase content ofdensity window V. Acid phosphatase activity also redistributed following stimulation, but it was recruited from a different source, and it was inserted into membranes equilibrating inwindows II andIII as well as into the membranes ofwindow I. |
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Keywords: | exocrine glands fluid and electrolyte secretion cell volume regulation Golgi complex membrane recycling stimulus-secretion coupling |
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