Search results for "EGTA"

Comparison of the anticonstrictor action of dihydropyridines (nimodipine and nicardipine) and Mg2+ in isolated human cerebral arteries.

1992

The isometric tension recorded from ring segments of branches of human middle cerebral artery was the parameter used to study the inhibition of spasmogen-induced contractions as model for cerebral vasospasm. Concentration-response curves to 5-hydroxytryptamine (10(-9)-3 x 10(-5) M) and prostaglandin F2 alpha (10(-7)-3 x 10(-5) M) were inhibited in Ca(2+)-free medium and in Ca(2+)-free medium to which EGTA (1 mM) had been added, respectively. Nimodipine (10(-7), 10(-5) M), nicardipine (10(-7), 10(-5) M) and Mg2+ (magnesium sulfate 10(-4), 10(-2) M) inhibited the 5-HT-elicited contractions, and this inhibition was similar for the highest concentrations tested. In contrast, nimodipine and nica…

Effects of phorbol 12,13-diacetate on human isolated bronchus

2000

Protein kinase C appears to be involved in the regulation of airway contractility. Phorbol 12,13-diacetate (PDA; 0.01-10 microM), a protein kinase C activator, produced a transient relaxation followed by a sustained contraction of human isolated bronchus. Different protein kinase C inhibitors (calphostin C, staurosporine and 1-(5-isoquinolinesulfonyl)-2-methylpiperazine) (H-7), nifedipine (NIF; 1 microM) or incubation with Ca(2+)-free medium, inhibited the spasmogenic response to phorbol, while ouabain (10 microM) suppressed only the initial relaxation. These results indicate that the initial relaxation, in response to PDA, is related to the activation of Na(+)/K(+)-ATPase, while the ensuin…

[MnM(egta)]· 8H2O(M= Mn, Cd): A Novel Type of Two-Dimensional Magnetic Lattice

1993

Cadherin 23 is a component of the transient lateral links in the developing hair bundles of cochlear sensory cells

2005

AbstractCadherin 23 is required for normal development of the sensory hair bundle, and recent evidence suggests it is a component of the tip links, filamentous structures thought to gate the hair cells' mechano-electrical transducer channels. Antibodies against unique peptide epitopes were used to study the properties of cadherin 23 and its spatio-temporal expression patterns in developing cochlear hair cells. In the rat, intra- and extracellular domain epitopes are readily detected in the developing hair bundle between E18 and P5, and become progressively restricted to the distal tip of the hair bundle. From P13 onwards, these epitopes are no longer detected in hair bundles, but immunoreac…

Mast cells promote homeostasis by limiting endothelin-1-induced toxicity

2004

Endothelin-1 (ET-1) is a 21-amino-acid peptide, derived from vascular endothelial cells, with potent vasoconstrictor activity. ET-1 has been implicated in diverse physiological or pathological processes, including the vascular changes associated with sepsis. However, the factors that regulate ET-1-associated toxicity during bacterial infections, or in other settings, are not fully understood. Both the pathology associated with certain allergic and autoimmune disorders, and optimal host defence against bacterial and parasitic infections are mediated by mast cells. In vitro, mast cells can produce ET-1 (ref. 11), undergo ET-1-dependent and endothelin-A receptor (ET(A))-dependent activation, a…

EGTA treatment causes the synthesis of heat shock proteins in sea urchin embryos.

2000

Paracentrotus lividus embryos, at post-blastular stage, when subjected to a rise in temperature from physiologic (20 degrees C) to 31 degrees C, synthesize a large group of heat shock proteins (hsps), and show a severe inhibition of bulk protein synthesis. We show, by mono- and two-dimensional electrophoresis, that also EGTA (ethylene glycol-bis[beta-aminoethyl ether] tetraacetic acid) treatment induces in sea urchin embryos both marked inhibition of bulk protein synthesis and the synthesis of the entire set of hsps. Furthermore, EGTA-treated sea urchin embryos are able to survive at a temperature otherwise lethal (35 degrees C) becoming thermotolerant. Because incubation with a different c…

Heat-induced action potential discharges in nociceptive primary sensory neurons of rats.

2009

Although several transducer molecules for noxious stimuli have been identified, little is known about the transformation of the resulting generator currents into action potentials (APs). Therefore we investigated the transformation process for stepped noxious heat stimuli (42-47 degrees C, 3-s duration) into membrane potential changes and subsequent AP discharges using the somata of acutely dissociated small dorsal root ganglion (DRG) neurons (diameteror=32.5 microm) of adult rats as a model for their own peripheral terminals. Three types of heat-induced membrane potential changes were differentiated: type 1, heat-induced AP discharges (approximately 37% of the neurons); type 2, heat-induce…

Effects of Anandamide and Noxious Heat on Intracellular Calcium Concentration in Nociceptive DRG Neurons of Rats

2007

As an endogenous agonist at the cannabinoid receptor CB1 and the capsaicin-receptor TRPV1, anandamide may exert both anti- and pronociceptive actions. Therefore we studied the effects of anandamide and other activators of both receptors on changes in free cytosolic calcium ([Ca2+]i) in acutely dissociated small dorsal root ganglion neurons (diameter: ≤30 μm). Anandamide (10 μM) increased [Ca2+]iin 76% of the neurons. The EC50was 7.41 μM, the Hill slope was 2.15 ± 0.43 (mean ± SE). This increase was blocked by the competitive TRPV1-antagonist capsazepine (10 μM) and in Ca2+-free extracellular solution. Neither exclusion of voltage-gated sodium channels nor additional blockade of voltage-gate…

Influence of calcium on the effects of okadaic acid and its interaction with caffeine and theophylline in rat myometrium.

1994

The effects of okadaic acid (OA), a monocarboxylic acid produced by marine dinoflagellates belonging to the genera Dinophysis and Prorocentrum, and their interactions with theophylline and caffeine were studied on the rat-isolated uterus in a calcium-containing medium and a calcium-free medium in the presence of 10−3 M EGTA. Okadaic acid (5 × 10−6 to 5 × 10−5 M) induced a concentration-dependent contraction of the rat-isolated uterus corresponding, with 5 × 10−5M, to 142.3±6.1% (n = 7) of the contraction induced by oxytocin 10−6 M. The time to peak tension was inversely proportional to the maximum effect produced. The contraction was not sustained and was followed by a concentration-depende…

LTV1 raidījuma „Aizliegtais paņēmiens” ētiskie aspekti

2015

Bakalaura darba tēma ir LTV1 Raidījuma „Aizliegtais paľēmiens” ētiskie aspekti. Darba mērķis ir izpētīt raidījuma saturu, noskaidrot, vai tajā tiek ievēroti ţurnālistikas ētikas principi un vērtības, noteikt raidījuma mērķus un izmantotos līdzekļus, kā arī to saskaľotību, veicot raidījuma izpēti aptuveni gada garumā. Teorija balstīta par televīziju, pētnieciskās ţurnālistikas teorētisko raksturojumu, ētiku un ţurnālistikas ētikas pamatprincipiem. Izvēlētās pētniecības metodes ir kvantitatīvā un kvalitatīvā kontentanalīze, kā arī daļēji strukturētās intervijas. Pētījumā secināts, ka tiek pārkāpti ţurnālistikas ētikas principi, un izmantotie datu vākšanas līdzekļi ne vienmēr attaisno mērķi. A…