Comparison of parathyroid hormone and calcium ionophore A23187 effects on bone resorption and nucleic acid synthesis in cultured fetal rat bone

1982 ◽  
Vol 34 (1) ◽  
pp. 495-500 ◽  
Author(s):  
T. F. DeBartolo ◽  
L. E. Pegg ◽  
C. Shasserre ◽  
T. J. Hahn
Keyword(s):  
Parathyroid Hormone ◽  
Nucleic Acid ◽  
Bone Resorption ◽  
Calcium Ionophore ◽  
Acid Synthesis ◽  
Calcium Ionophore A23187 ◽  
Nucleic Acid Synthesis ◽  
Ionophore A23187 ◽  
Fetal Rat ◽  
Rat Bone

The role of calcium and calmodulin in mediating release of thyrotrophin-releasing hormone by cultured hypothalamic cells

1987 ◽  
Vol 115 (2) ◽  
pp. 255-262 ◽  
Author(s):  
M. D. Lewis ◽  
S. M. Foord ◽  
M. F. Scanlon
Keyword(s):  
Cell Cultures ◽  
Calcium Influx ◽  
Calcium Ionophore ◽  
Reversed Phase ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Calmodulin Antagonist ◽  
Thyrotrophin Releasing Hormone ◽  
Fetal Rat ◽  
Basal Release

ABSTRACT We have developed a fetal rat hypothalamic cell culture system for the study of factors controlling the acute release of TRH. Release of TRH by the cells has been characterized by reversed-phase high pressure liquid chromatography and about 86% of the total immunoreactivity in the medium co-eluted with synthetic TRH. Release of TRH by the cells in response to 56 mmol K+/l increased between days 5 and 9 of culture but reached a plateau thereafter. Cell contents of TRH did not change significantly between days 5 and 14 of culture. Release of TRH from the cells was stimulated by K+ (56 mmol/l), veratridine (100 μmol/l) and ouabain (100 μmol/l) to 550, 480 and 335% of basal release respectively over a 1-h period. Release of TRH was dependent upon calcium in that it was absent when calcium-free medium was used and could be blocked by verapamil (20 μmol/l); however it could not be blocked by nifedipine (50 μmol/l). The calcium ionophore A23187 (1 μmol/l) stimulated TRH release to 340% of basal release. Tetrodotoxin (1 μmol/l) completely abolished the release in response to veratridine but had no effect on the release stimulated by K+ (56 mmol/l). The calmodulin antagonists trifluoperazine and triflupromazine (50 μmol/l) inhibited veratridine-stimulated TRH release. This was at a site after calcium influx as they also inhibited A23187-stimulated TRH release. The highly specific calmodulin antagonist W7 (10 μmol/l) also inhibited both veratridine and A23187-stimulated TRH release whereas, at the same concentration, its inactive analogue W5 did not significantly inhibit TRH release in response to either stimulus. These results confirm that fetal rat hypothalamic cell cultures release authentic TRH which can be stimulated by a number of depolarizing agents. Calcium is essential for depolarization-induced release which is also dependent on calmodulin. Fetal rat hypothalamic cell cultures are a valid model for the study of factors controlling the release of TRH. J. Endocr. (1987) 115, 255–262

Synthesis and secretion of somatostatin-28 and -14 by fetal rat intestinal cells in culture

1990 ◽  
Vol 258 (6) ◽  
pp. G974-G981 ◽  
Author(s):  
P. L. Brubaker ◽  
D. J. Drucker ◽  
G. R. Greenberg
Keyword(s):  
Phorbol Ester ◽  
Calcium Ionophore ◽  
Immunohistochemical Analysis ◽  
Calcium Ionophore A23187 ◽  
Intestinal Cell ◽  
Gel Chromatography ◽  
Ionophore A23187 ◽  
Concomitant Treatment ◽  
Fetal Rat ◽  
A Minor

A fetal rat intestinal cell (FRIC) culture model was established to investigate the factors controlling synthesis and secretion of somatostatin-28 (S-28) by the intestine. Immunohistochemical analysis demonstrated the presence of cells containing somatostatin-like immunoreactivity (SLI), many of which emitted long processes toward neighboring cells. Gel chromatography of SLI stored and secreted by nonstimulated FRIC cultures demonstrated a predominance of S-28 (59%), lesser amounts of S-14 (31%), and a minor peak of large molecular weight SLI (10%). Secretion of SLI was stimulated by treatment of cells for 2 h with 5 mM dibutyryl adenosine 3',5'-cyclic monophosphate (DBcAMP; P less than 0.01) or 2 microM phorbol ester (P less than 0.05), but was unaffected by the calcium ionophore A23187 (2 micrograms/ml). Concomitant treatment with all three agents increased SLI secretion in an additive fashion to 254 +/- 25% of controls (P less than 0.0001). DBcAMP treatment did not alter the distribution of stored or secreted S-28 (59%) and S-14 (33%). After 24 h of exposure to DBcAMP, but not after treatment with phorbol ester, a threefold increment in prosomatostatin mRNA transcript levels was observed. FRIC cultures therefore synthesize and secrete a predominance of S-28 in a regulated manner, making them a promising model for future studies on the biosynthesis and secretion of intestinal somatostatin.

Inhibition of parathyroid hormone-induced fetal rat bone resorption in vitro by nerve growth factor

1978 ◽  
Vol 26 (1) ◽  
pp. 203-208 ◽  
Author(s):  
Steven L. Teitelbaum ◽  
Roger Y. Andres ◽  
Nancy E. Cooke ◽  
Theodore J. Hahn ◽  
Arnold J. Kahn
Keyword(s):  
Parathyroid Hormone ◽  
Nerve Growth Factor ◽  
Growth Factor ◽  
Bone Resorption ◽  
Nerve Growth ◽  
Fetal Rat ◽  
Rat Bone

Growth factors and the primary cilium in BALB/c 3T3 cells

1987 ◽  
Vol 45 ◽  
pp. 830-831
Author(s):  
R. W. Tucker ◽  
N. S. More ◽  
S. Jayaraman
Keyword(s):  
Growth Factors ◽  
Primary Cilium ◽  
Cultured Cells ◽  
Morphological Changes ◽  
Calcium Ionophore ◽  
Growth Stimulation ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
3T3 Cells ◽  
Microtubule Depolymerization

The mechanisms by which polypeptide growth factors Induce DNA synthesis in cultured cells is not understood, but morphological changes Induced by growth factors have been used as clues to Intracellular messengers responsible for growth stimulation. One such morphological change has been the transient disappearance of the primary cilium, a “9 + 0” cilium formed by the perinuclear centriole in interphase cells. Since calcium ionophore A23187 also produced both mitogenesis and ciliary changes, microtubule depolymerization might explain ciliary disappearance monitored by indirect immunofluorescence with anti-tubulin antibody. However, complete resorption and subsequent reformation of the primary cilium occurs at mitosis, and might also account for ciliary disappearance induced by growth factors. To settle this issue, we investigated the ultrastructure of the primary cilium using serial thin-section electron microscopy of quiescent BALB/c 3T3 cells before and after stimulation with serum.

Inhibition of Platelet Aggregation by Ethanol in Vitro Shows Specificity for Aggregating Agent Used and Is Influenced by Platelet Lipid Composition

1982 ◽  
Vol 48 (01) ◽  
pp. 049-053 ◽  
Author(s):  
C G Fenn ◽  
J M Littleton
Keyword(s):  
Platelet Aggregation ◽  
Lipid Composition ◽  
Saturated Fatty Acids ◽  
Calcium Ionophore ◽  
Cholesterol Content ◽  
Membrane Lipid ◽  
Calcium Ionophore A23187 ◽  
Ionophore A23187 ◽  
Increased Sensitivity

SummaryEthanol at physiologically tolerable concentrations inhibited platelet aggregation in vitro in a relatively specific way, which may be influenced by platelet membrane lipid composition. Aggregation to collagen, calcium ionophore A23187 and thrombin (low doses) were often markedly inhibited by ethanol, adrenaline and ADP responses were little affected, and aggregation to exogenous arachidonic acid was actually potentiated by ethanol. Aggregation to collagen, thrombin and A23187 was inhibited more by ethanol in platelets enriched with saturated fatty acids than in those enriched with unsaturated fats. Platelets enriched with cholesterol showed increased sensitivity to ADP, arachidonate and adrenaline but this increase in cholesterol content did not appear to influence the inhibition by ethanol of platelet responses. The results suggest that ethanol may inhibit aggregation by an effect on membrane fluidity and/or calcium mobilization resulting in decreased activity of a membrane-bound phospholipase.

Influence of Inhibitors of Nucleic Acid Synthesis and Protein Synthesis on Glutamine Synthetase Gene Expression Induced by Nitrogen in Sugar Beet (Beta vulgaris L.)

2009 ◽  
Vol 35 (3) ◽  
pp. 445-451
Author(s):  
Sheng-Yong CHEN ◽  
Jing HOU ◽  
Cai-Feng LI ◽  
Feng-Ming MA ◽  
Chun-Jia YIN ◽  
...  
Keyword(s):  
Gene Expression ◽  
Protein Synthesis ◽  
Nucleic Acid ◽  
Glutamine Synthetase ◽  
Sugar Beet ◽  
Beta Vulgaris ◽  
Acid Synthesis ◽  
Nucleic Acid Synthesis ◽  
Glutamine Synthetase Gene
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