Search results for "EGTA"
showing 10 items of 35 documents
Sphingosine-1-phosphate increases human alveolar epithelial IL-8 secretion, proliferation and neutrophil chemotaxis
2009
Sphingosine-1-phosphate (S1P) has been presented recently as a pro-inflammatory agent in the airway epithelium since S1P levels are increased in bronchoalveolar lavage fluid of human asthmatics. However, the effects of S1P over the alveolar epithelium and neutrophil interactions are poorly understood. Here, we show that S1P increased interleukin 8 (IL-8) gene expression and protein secretion and proliferation in alveolar epithelial cells A549 at physiological concentrations (1 microM). At the same time, S1P increased intracellular Ca2+ concentration (potency 17.91 microM, measured by epifluorescence microscopy), phospholipase D (PLD) activity (measured by chemiluminiscence method) and extra…
The effects of phorbol esters on choline phospholipid hydrolysis in heart and brain
1990
The efflux of choline was determined in rat striatal slices, incubated chicken atria and perfused chicken hearts. 4 beta-Phorbol-12 beta,13 alpha-dibutyrate (PDB) and 4 beta-phorbol-12 beta-myristate, 13 alpha-acetate (PMA) were used to stimulate protein kinase C. The other phorbol esters, 4 beta-phorbol-13 alpha-acetate (PAc) and 4 alpha-phorbol-12 beta,13 alpha-didecanoate (4 alpha PDD), known to be inactive, were tested to evaluate the specificity of the responses. PDB markedly enhanced the efflux of choline in all of the three preparations. The PDB-evoked efflux of choline in incubated chicken atria was equal to the net production of choline and, therefore, was not caused by translocati…
Mouse photoreceptor synaptic ribbons lose and regain material in response to illumination changes
2004
Abstract Chemical synapses equipped with ribbons are tonically active, high-output synapses. The ribbons may play a role in the trafficking of synaptic vesicles. Recent findings in retinal rod cells of BALB/c mice indicate that ribbons are large and smooth in the dark phase, and, due to the formation and release of protrusions, small during the light phase. As a consequence of these changes, ribbons may traffick fewer vesicles in the light than in the dark phases. The aim of the present study was to find out whether the above ribbon changes in this mouse strain are strictly illumination-dependent and which signalling processes may be involved. Here, we show that ribbons form protrusions and…
Characterization of a Ryanodine Receptor inPeriplaneta Americana
1997
Specific binding sites for the alkaloid ryanodine were characterized in membrane preparations from sarcoplasmatic reticulum of Periplaneta americana skeletal muscle. Binding of [3H]ryanodine was optimal at pH 8 and at CaCl2 concentration of about 300 mumol l-1. The Ca-chelating agents EGTA (100 mumol l-1) and EDTA (100 mumol l-1) abolished 95% and 90% of the [3H]ryanodine binding respectively. Preincubation with Ca2+ (100 mumol l-1) restored the ryanodine binding in presence of up to 300 mumol l-1 EGTA. Radioligand binding experiments showed one class of high affinity binding sites for ryanodine. Determination of rate constants revealed 7.05 x 10(6) l mol-1 min-1 for associating and 3.77 x …
Cholinergic and GABAergic regulation of nitric oxide synthesis in the guinea pig ileum.
1999
Nitric oxide (NO) synthesis was examined in intact longitudinal muscle-myenteric plexus preparations of the guinea pig ileum by determining the formation of [3H]citrulline during incubation with [3H]arginine. Spontaneous [3H]citrulline production after 30 min was 80–90 dpm/mg, which constituted ∼1% of the tissue radioactivity. Electrical stimulation (10 Hz) led to a threefold increase in [3H]citrulline formation. Removal of calcium from the medium or addition of N G-nitro-l-arginine strongly inhibited both spontaneous and electrically induced production of [3H]citrulline. TTX reduced the electrically induced but not spontaneous [3H]citrulline formation. The electrically induced formation o…
Effects of low temperature and pharmacological interventions on the responses of the isolated guinea-pig trachea
1992
Cooling the guinea-pig isolated trachea from 37°C to 20°C virtually abolished the response to CaCl2 (in K+-depolarized tissues) and depressed that to histamine (about 75% reduction), KCl and 5-hydroxytryptamine (around 50% inhibition) while the response to acetylcholine remained unaffected. A further cooling to 10°C was necessary to inhibit acetylcholine-induced contractions. Hyporesponsiveness to spasmogens by cooling was not associated with subsensitivity (increased EC50) except for 5-hydroxytryptamine. Contractile responses to KCl (50 mmol/l), histamine (1 mmol/l) and 5-hydroxytryptamine (0.1 mmol/l) in a Ca2+-free EGTA (0.1 mmol/l)-containing solution were inhibited by cooling to 20°C b…
EFFECTS OF VANADATE ON RESPONSES OF GUINEA-PIG ISOLATED TRACHEA TO SPASMOGENS
1993
Abstract The effects of vanadate on the contractility of the guinea-pig isolated trachea was examined. Vanadate (0·1 Mm) produced a sustained contraction that was abolished in Ca2+-free EGTA (0·1 Mm)-containing physiological salt solution but was resistant to verapamil (1 μm). Vanadate (0·1 Mm) depressed tracheal responses to CaCl2 (in Ca2+-free depolarizing solution), KCl, acetylcholine, histamine and 5-hydroxytryptamine. For vanadate (10 μm), the inhibition of spasmogenic responses only reached statistical significance for histamine and 5-hydroxytryptamine. Caffeine (1 Mm)-induced spasm (trachea at 20°C in the presence of indomethacin (2·8 μm)) was not affected by vanadate (10 μm-0·1 Mm).…
Effects of Ca2+ entry blockers on CaCl2-, KCl- and noradrenaline-induced contractions of goat cerebral arteries
1990
Abstract The effects of three Ca 2+ entry blockers, nicardipine, nimodipine and verapamil, on CaCl 2 -, KCl- and noradrenaline-induced contractions were examined in isolated goat middle cerebral artery. The relationship between the effects of Ca 2+ entry blockers and the extracellular Ca 2+ dependence of the contractions was also examined. In ‘nominally’ Ca 2+ -free medium, addition of CaCl 2 induced concentration-dependent contractions of previously depolarized arteries. Withdrawal of Ca 2+ from the extracellular medium caused strong inhibition of the KCl- and noradrenaline-induced arterial contractions. Addition of EGTA to the Ca 2+ -free medium almost abolished the noradrenaline-response…
NADPH-diaphorase activity of nitric oxide synthase in the olfactory bulb: co-factor specificity and characterization regarding the interrelation to N…
1994
The neuronal form of the enzyme nitric oxide synthase (nNOS) synthesizes the messenger molecule nitric oxide (NO). In addition to NO formation, nNOS exhibits a so-called NADPH-diaphorase (NADPH-d) activity. This study focused on the characterization of NADPH-d activity with regard to NO formation in the rat olfactory bulb. In this area of the brain pronounced staining is localized in discrete populations of neuronal somata and in olfactory glomeruli. Diaphorase staining combined with demonstration of nNOS by polyclonal antibodies revealed that NADPH-d activity of neuron somata is associated with nNOS immunoreactivity. It is concluded that neuron somata exhibit NADPH-d activity of nNOS. NAD…
Extracellular calcium-sensing receptor mediates human bronchial epithelial wound repair
2010
The airway epithelium routinely undergoes damage that requires repair to restore epithelial barrier integrity. Cell migration followed by proliferation are necessary steps to achieve epithelial repair. Calcium-sensing receptor (CaSR) is implicated in cell migration and proliferation processes. Thus we hypothesized that CaSR mediates lung epithelial wound repair. We detected CaSR expression in human lung and in well-differentiated human bronchial epithelial cells (HBEC). To test the CaSR functionality, HBEC loaded with fura-2 were stimulated with extracellular Ca(2+) ([Ca(2+)](out)) which resulted in a concentration-dependent intracellular Ca(2+) ([Ca(2+)](i)) increase (potency approximately…