1.Roles of intracellular calcium and monomeric G-proteins in regulating exocytosis of human neutrophils.
Ying ZHU ; Jun-Han WANG ; Jian-Min WU ; Tao XU ; Chun-Guang ZHANG
Acta Physiologica Sinica 2003;55(6):699-704
Neutrophils play a major role in host defense against microbial infection. There are some clues indicate that neutrophils may also play a role in the pathophysiology of the airway obstruction in chronic asthma. We studied the roles of intracellular calcium and GTP gamma S in the regulation of neutrophils exocytosis using pipette perfusion and membrane capacitance measurement technique in whole cell patch clamp configuration. The results showed that the membrane capacitance increase induced by calcium revealed a biphasic process. The first phase occurred when the calcium level was between 0.2-14 micromol/L with a plateau amplitude of 1.23 pF and a calcium EC50 of 1.1 micromol/L. This phase might correspond to the release of the tertiary granules. The second phase occurred when the calcium concentration was between 20-70 micromol/L with a plateau increment of 6.36 pF, the calcium EC50 being about 33 micromol/L. This phase might represent the release of the primary and secondary granules. Intracellular calcium also simultaneously increased the exocytotic rate and the eventual extent in neutrophils. On the other hand, GTP gamma S can increase the exocytotic rate in a dose-dependent manner but had no effect on the eventual extent of membrane capacitance increment (>6 pF) if the cell was stimulated for a long period (>20 min). GTP gamma S (ranging from 20 to 100 micromol/L) induced the neutrophils to release all four types of the granules at very low intracellular calcium level.
Calcium
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metabolism
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Cell Degranulation
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drug effects
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Exocytosis
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drug effects
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GTP-Binding Proteins
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metabolism
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physiology
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Guanosine Triphosphate
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analogs & derivatives
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pharmacology
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Humans
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Neutrophils
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metabolism
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physiology
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Patch-Clamp Techniques
2.Expression of Ca2+-dependent Synaptotagmin Isoforms in Mouse and Rat Parotid Acinar Cells.
Hae JO ; Hae Mi BYUN ; Jong Hoon KIM ; Min Seuk KIM ; Seung Hyeoi KIM ; Jeong Hee HONG ; Jeong Taeg SEO ; Syng Ill LEE ; Dong Min SHIN ; Heung Kyu SON
Yonsei Medical Journal 2006;47(1):70-77
Synaptotagmin is a Ca2+ sensing protein, which triggers a fusion of synaptic vesicles in neuronal transmission. Little is known regarding the expression of Ca2+ - dependent synaptotagmin isoforms and their contribution to the release of secretory vesicles in mouse and rat parotid acinar cells. We investigated a type of Ca2+ - dependent synaptotagmin and Ca2+ signaling in both rat and mouse parotid acinar cells using RT-PCR, microfluorometry, and amylase assay. Mouse parotid acinar cells exhibited much more sensitive amylase release in response to muscarinic stimulation than did rat parotid acinar cells. However, transient [Ca2+]i increases and Ca2+ influx in response to muscarinic stimulation in both cells were identical, suggesting that the expression or activity of the Ca2+ sensing proteins is different. Seven Ca2+ - dependent synaptotagmins, from 1 to 7, were expressed in the mouse parotid acinar cells. However, in the rat parotid acinar cells, only synaptotagmins 1, 3, 4 and 7 were expressed. These results indicate that the expression of Ca2+ - dependent synaptotagmins may contribute to the release of secretory vesicles in parotid acinar cells.
Synaptotagmins/*metabolism
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Signal Transduction
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Rats
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Protein Isoforms/metabolism
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Parotid Gland/cytology/*metabolism
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Muscarinic Agonists/pharmacology
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Mice
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Exocytosis/drug effects/physiology
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Carbachol/pharmacology
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Calcium/metabolism/*physiology
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Animals
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Amylases/secretion
3.Observation of insulin exocytosis by a pancreatic β cell line with total internal reflection fluorescence microscopy.
Zhao-ying FU ; Ya-ping WANG ; Yu CHEN
Chinese Medical Sciences Journal 2011;26(1):60-63
Animals
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Exocytosis
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drug effects
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physiology
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Glucose
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pharmacology
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Insulin
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secretion
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Insulin-Secreting Cells
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cytology
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drug effects
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metabolism
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Mice
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Microscopy, Fluorescence
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methods
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Potassium
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pharmacology
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Recombinant Fusion Proteins
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genetics
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metabolism
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Vesicle-Associated Membrane Protein 2
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genetics
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metabolism
4.Na+i, K+i and Cl-i regulation of exocytosis in guinea-pig antral mucous cells.
Takashi NAKAHARI ; Shoko FUJIWARA ; Chikao SHIMAMOTO
Journal of Korean Medical Science 2000;15(Suppl):S36-S37
Effects of intracellular Na+, K+ and Cl- on Ca(2+)-regulated exocytosis activated by 10 microM acetylcholine (ACh) were studied in guinea-pig antral mucous cells which are permeabilized by nystatin treatment. Ca(2+)-regulated exocytotic events were modulated by [Na+]i, [K+]i and [Cl-]i via mediation of PTX-sensitive G proteins. Increases in [Na+]i and PTX inhibit G protein (G(Na)), which suppressed the exocytosis. Increases in [K+]i caused the exchange of G proteins (from G(Na) to G(K)) to increase, and GK evoked activation of the exocytosis and was inhibited by PTX. Increases in [Cl-]i and PTX inhibit G protein (G(Cl)), which stimulates exocytotic events. Based on these observations, the exocytosis in antral mucous cells were modulated by intracellular ions, concentration of which were increased or decreased by cell volume changes caused by Ach.
Acetylcholine/pharmacology
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Animal
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Cell Membrane Permeability/drug effects
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Exocytosis/physiology*
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Exocytosis/drug effects
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Gastric Mucosa/metabolism
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Gastric Mucosa/cytology
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Guinea Pigs
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Hypertonic Solutions/pharmacology
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Ionophores/pharmacology
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Nystatin/pharmacology
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Pertussis Toxins/pharmacology
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Potassium/pharmacokinetics*
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Pyloric Antrum/metabolism*
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Pyloric Antrum/cytology
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Sodium Chloride/pharmacokinetics*
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Vasodilator Agents/pharmacology