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β‐Adrenergic Stimulation Increases Protein Secretion But Not Fluid Flow in Mouse Lacrimal Gland
Author(s) -
Huang Wei Chieh,
Sato Michiko,
Moore Leon C,
Walcott Benjamin,
Brink Peter R
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a836-d
Subject(s) - secretion , endocrinology , medicine , carbachol , chemistry , stimulation , adrenergic , lacrimal gland , secretagogue , acinus , receptor , biology , pancreas , pathology
Activation of either α‐ and β‐adrenergic receptors is known to induce protein secretion from isolated acinar cells and gland fragments. Here, we determined if β‐adrenergic receptor activation with isoproterenol (ISO) stimulates fluid secretion. In anesthetized C57 mice, fluid flow from the lacrimal duct was measured in calibrated microcapillaries via videomicroscopy; secretion was elicited by adding 10 μM carbachol (CARB) or ISO to the fluid bathing the gland. Acinar cells were isolated and plated on matrigel. After 24 h, cells were exposed to CARB or ISO and changes in cell volume and membrane currents were measured via videomicroscopy and patch‐clamping. In intact glands, CARB elicited a prompt, reversible rise in tear flow, but ISO had no detectable effect. In isolated cells, CARB induced a ~10% shrinkage, consistent with the onset of fluid secretion. ISO had no effect on cell volume in ~80% of cells studied (n=26 total); ~20% showed marked shape changes and a variable degree of shrinkage that may be associated with protein secretion. CARB resulted in marked increases in outward and inward membrane currents consistent with activation of K + and Cl − channels; the currents were much lower with ISO and ½ of the cells did not show any response, despite normal resting potential and currents. Conclusion β‐adrenergic does not stimulate lacrimal fluid secretion. This result supports the concept that there is differential regulation of water and protein secretion in lacrimal gland. Funded by NIH EY 14604