Post-weaning xenohormone intake affects adult rat submandibular gland in a sex-dependent manner

Rat submandibular acinar cells exhibit a tetraethylammonium (TEA)-insensitive, Ca2+-activated K+ conductance, which may play an important role in Ca2+-dependent fluid secretion by this gland (T. Ishikawa, M. Murakami, and Y. Seo. Pfluegers Arch. 428: 516-525, 1994; T. Ishikawa and M. Murakami. Pfluegers Arch. 429: 748-750, 1995). We have now investigated whether this conductance would be modified during the potentiation of Ca2+-activated fluid secretion by an adenosine 3',5'-cyclic monophosphate (cAMP)-mediated mechanism in the rat submandibular gland. In isolated, vascularly perfused rat submandibular gland, we found that the adenylate cyclase activator forskolin (10 and 30 microM) enhanced a transient initial phase of a biphasic fluid secretion induced by the Ca2+ ionophore A-23187 (3 microM). We also unexpectedly found that forskolin reduced a smaller sustained phase of the secretion. The dual effects of forskolin were mimicked by the application of the cocktail of 3-isobutyl-1-methylxanthine (IBMX) (0.1 mM) and dibutyryl cAMP (DBcAMP) (0.1 and 0.5 mM). Basolateral K+ efflux studies showed that 1) forskolin significantly enhanced a large transient net K+ efflux induced by A-23187 in a dose-dependent manner; 2) the forskolin-induced enhancement was also mimicked by a cocktail of IBMX and DBcAMP; and 3) the A-23187-induced K+ efflux enhanced by these agents was not inhibited by TEA (5 or 10 mM), a concentration known to completely block Ca2+ voltage-dependent large-conductance K+ channels (maxi-K+ channels). With use of microspectrofluorometry with fura 2, we then showed that an increase in cytosolic Ca2+ concentration induced by the nonfluorescent, brominated derivative 4-bromo-A-23187 (3 microM) was not altered by forskolin (30 microM) in freshly isolated rat submandibular acinar cells. With use of whole cell patch-clamp techniques, we demonstrated that a TEA-insensitive K+ conductance induced by A-23187 in cells dialyzed with pipette solutions containing cAMP (0.1 mM) was significantly larger than that in cells treated with control pipette solutions. Taken together, these results indicate that potentiation of the Ca2+-activated fluid secretion by a cAMP-mediated mechanism is accompanied by potentiation of a TEA-insensitive, Ca2+-activated K+ conductance in this gland.

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Characterization and partial purification of rat submandibular gland protein kinase C

Biochemistry and Cell Biology ◽

10.1139/o88-078 ◽

1988 ◽

Vol 66 (7) ◽

pp. 683-690

Author(s):

D. J. Pon ◽

S. P. Lintlop ◽

A. K. Sen

Keyword(s):

Protein Kinase C ◽

Protein Kinase ◽

Submandibular Gland ◽

Kinase Activity ◽

Partial Purification ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Kinase C ◽

Membrane Bound ◽

Rat Submandibular Gland

Membrane-bound protein kinase C of rat submandibular gland was characterized and the cytosolic kinase C of the tissue was partially purified. The membrane-bound kinase could be activated by Triton X-100 but not EGTA in the presence of both Ca2+ and phosphatidylserine (PS). The Km values for Ca2+ and PS were 150 μM and 5 μg, respectively. Addition of 10−6 M diacylglycerol resulted in an increased affinity of the kinase for Ca2+ (Km = 10 μM). Phorbol 12,13-dibutyrate activated the kinase in the absence of exogenous Ca2+ and PS, suggesting that adequate amounts of each activator are present in the membrane itself. Polymyxin B inhibited the stimulated kinase C activity in a concentration-dependent manner. This inhibition could be overcome by addition of PS. The cytosolic kinase was partially purified 133-fold by chromatography on columns of DEAE-Sephacel and S-300 Sephacryl. The total kinase activity increased with respect to the kinase activity measured in the starting material with column chromatography, suggesting that an inhibitor is present in the cytosolic fraction of the tissue.

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Selection of housekeeping genes for gene expression studies in the adult rat submandibular gland under normal, inflamed, atrophic and regenerative states

BMC Molecular Biology ◽

10.1186/1471-2199-9-64 ◽

2008 ◽

Vol 9 (1) ◽

pp. 64 ◽

Cited By ~ 32

Author(s):

Nicholas Silver ◽

Emanuele Cotroneo ◽

Gordon Proctor ◽

Samira Osailan ◽

Katherine L Paterson ◽

...

Keyword(s):

Gene Expression ◽

Submandibular Gland ◽

Housekeeping Genes ◽

Adult Rat ◽

Expression Studies ◽

Gene Expression Studies ◽

Rat Submandibular Gland ◽

Selection Of

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Cytochemical Evidence for Presynatic β-Adrenergic Regulation of Secretion in the Developing Rat Submandibular Gland

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100079590 ◽

1977 ◽

Vol 35 ◽

pp. 430-431

Author(s):

L.S. Cutler

Keyword(s):

Cyclic Amp ◽

Adenylate Cyclase ◽

Submandibular Gland ◽

Neonatal Rat ◽

Cyclase Activity ◽

Adenylate Cyclase Activity ◽

Parotid Glands ◽

Adrenergic Agonist ◽

Rat Submandibular Gland

Many studies previously have shown that the B-adrenergic agonist isoproterenol and the a-adrenergic agonist norepinephrine will stimulate secretion by the adult rat submandibular (SMG) and parotid glands. Recent data from several laboratories indicates that adrenergic agonists bind to specific receptors on the secretory cell surface and stimulate membrane associated adenylate cyclase activity which generates cyclic AMP. The production of cyclic AMP apparently initiates a cascade of events which culminates in exocytosis. During recent studies in our laboratory it was observed that the adenylate cyclase activity in plasma membrane fractions derived from the prenatal and early neonatal rat submandibular gland was retractile to stimulation by isoproterenol but was stimulated by norepinephrine. In addition, in vitro secretion studies indicated that these prenatal and neonatal glands would not secrete peroxidase in response to isoproterenol but would secrete in response to norepinephrine. In contrast to these in vitro observations, it has been shown that the injection of isoproterenol into the living newborn rat results in secretion of peroxidase by the SMG (1).

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