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  • 1
    Digitale Medien
    Digitale Medien
    Sodium/Proton Exchange in Cultured Bovine Adrenal Medullary Cells (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 54 (1990), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: We investigated the presence of Na+/H+ exchange in cultured bovine adrenal medullary cells. The intracellular pH in control cells measured by 5,5-dimethyl[2-14C]oxazolidine-2,4-dione was 7.13 ± 0.02 (n = 6). Removal of Na+ from the incubation medium shifted the intracellular pH down to 6.67 ± 0.12 (n = 6). Reintroduction of Na+ to the medium caused a rapid recovery in intracellular pH to 7.20–7.30 that was associated with an increase in uptake of 22Na+ by the cells. Both increases in intracellular pH and uptake of 22Na+ were inhibited by amiloride, an inhibitor of Na+/H+ exchange. The recovery of intracellular pH by addition of Na+ was partially inhibited by quinidine, another inhibitor of Na+/H+ exchange, but not by 4-acetamido-4′-isothiocyanostilbene-2,2′-disulfonic acid, an anion-exchange (Cl−/HCO−3) inhibitor. Li+ could substitute for Na+ in the recovery of intracellular pH. Carbachol caused an increase in intracellular pH from 7.12 ± 0.01 to 7.21 ± 0.02 (n = 10). This increase in intracellular pH caused by carbachol was inhibited by amiloride. These results suggest the existence of an amiloride-sensitive Na+/H+ exchange that regulates the intracellular pH in adrenal medullary cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1471-4159.1990.tb01214.x
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  • 2
    Digitale Medien
    Digitale Medien
    Down-Regulation of the Noradrenaline Transporter by Interferon-α in Cultured Bovine Adrenal Medullary Cells (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: The aim of this study was to investigate the effect of long-term treatment with interferon (IFN)-α on the noradrenaline transporter of bovine adrenal medullary cells. Treatment of cultured adrenal medullary cells with IFN-α caused a decrease in uptake of [3H]noradrenaline by the cells in time (4–48 h)- and concentration (300–1,000 U/ml)-dependent manners. IFN-β also inhibited [3H]noradrenaline uptake to a lesser extent than did IFN-α, whereas IFN-γ had little effect. An anti-IFN-α antibody reduced the effect of IFN-α on [3H]noradrenaline uptake. Saturation analysis of [3H]noradrenaline uptake showed that the inhibitory effect of IFN-α was due to a reduction in the maximal uptake velocity (Vmax) values without altering apparent Michaelis constant (Km) values. Incubation of cells with IFN-α caused a translocation of protein kinase C from the soluble to the particulate fraction in the cells. The effect of IFN-α on [3H]noradrenaline uptake was diminished in protein kinase C-down-regulated cells. Incubation of cells with IFN-α for 48 h significantly reduced the specific binding of [3H]desipramine to crude plasma membranes isolated from cells. Scatchard analysis of [3H]desipramine binding revealed that IFN-α decreased the maximal binding (Bmax) values without any change in the dissociation constant (KD) values. These findings suggest that IFN-α suppresses the function of noradrenaline transporter by reducing the density of the transporter in cell membranes through, at least in part, a protein kinase C pathway.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.1998.70041441.x
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  • 3
    Digitale Medien
    Digitale Medien
    Pituitary Adenylate Cyclase-Activating Polypeptide Causes Ca2+ Release from Ryanodine/Caffeine Stores Through a Novel Pathway Independent of Both Inositol Trisphosphates and Cyclic AMP in Bovine Adrenal Medullary Cells (1998)
    Oxford, UK : Blackwell Science Ltd
    Journal of neurochemistry 70 (1998), S. 0 
    Details
    ISSN: 1471-4159
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin
    Notizen: Abstract: Pituitary adenylate cyclase-activating polypeptide (PACAP) causes both Ca2+ release and Ca2+ influx in bovine adrenal chromaffin cells. To elucidate the mechanisms of PACAP-induced Ca2+ release, we investigated expression of PACAP receptors and measured inositol trisphosphates (IP3), cyclic AMP, and the intracellular Ca2+ concentration in bovine adrenal medullary cells maintained in primary culture. RT-PCR analysis revealed that bovine adrenal medullary cells express the PACAP receptor hop, which is known to couple with both IP3 and cyclic AMP pathways. The two naturally occurring forms of PACAP, PACAP38 and PACAP27, both increased cyclic AMP and IP3, and PACAP38 was more potent than PACAP27 in both effects. Despite the effects of PACAP on IP3 production, the Ca2+ release induced by PACAP38 or by PACAP27 was unaffected by cinnarizine, a blocker of IP3 channels. The potencies of the peptides to cause Ca2+ release in the presence of cinnarizine were similar. The Ca2+ release induced by PACAP38 or by PACAP27 was strongly inhibited by ryanodine and caffeine. In the presence of ryanodine and caffeine, PACAP38 was more potent than PACAP27. PACAP-induced Ca2+ release was unaffected by Rp-adenosine 3′,5′-cyclic monophosphothioate, an inhibitor of protein kinase A. Ca2+ release induced by bradykinin and angiotensin II was also inhibited by ryanodine and caffeine, but unaffected by cinnarizine. Although IP3 production stimulated by PACAP38 or bradykinin was abolished by the phospholipase C inhibitor, U-73122, Ca2+ release in response to the peptides was unaffected by U-73122. These results suggest that PACAP induces Ca2+ release from ryanodine/caffeine stores through a novel intracellular mechanism independent of both IP3 and cyclic AMP and that the mechanism may be the common pathway through which peptides release Ca2+ in adrenal chromaffin cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1046/j.1471-4159.1998.70041652.x
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  • 4
    Digitale Medien
    Digitale Medien
    Veratridine causes the Ca2+-dependent increase in diacylglycerol formation and translocation of protein kinase C to membranes in cultured bovine adrenal medullary cells (1992)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 346 (1992), S. 76-81 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Amiloride ; Calcium ; Diacylglycerol ; Protein kinase C ; Veratridine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Our previous studies suggested that protein kinase C is involved in the veratridine (an activator of voltage-dependent Na+ channels)-induced phosphorylation and activation of tyrosine hydroxylase as well as the synthesis of catecholamines in adrenal medulla (Uezono et al. 1989). In the present study, we investigated whether treatment of cultured bovine adrenal medullary cells with veratridine causes the accumulation of diacylglycerol, a physiological activator of protein kinase C and the translocation of protein kinase C from cytosol to membrane, a process required for protein kinase C activation. Veratridine (100 μmol/l) increased diacylglycerol level about 2.2 fold in a monophasic manner, with peaking at 5 min and declining toward the basal level within 20 min. Veratridine also increased membrane protein kinase C from 15.6% to 26.9% of total protein kinase C in a timecourse similar to that of diacylglycerol accumulation. Both stimulatory effects of veratridine were inhibited by tetrodotoxin and not observed in Ca2+-free, EGTA-containing medium. Amiloride, an inhibitor of Na+/Ca2+ and Na+/H+ exchange, did not alter veratridine-induced events. These results suggest that veratridine-induced Ca2+ influx contributes to the accumulation of diacylglycerol and the activation of protein kinase C in adrenal medullary cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00167574
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  • 5
    Digitale Medien
    Digitale Medien
    Conotoxin GIIIA: selective inhibition of 22Na influx via voltage-dependent Na channels in adrenal medullary cells (1990)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 342 (1990), S. 323-327 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Adrenal medulla ; Catecholamine secretion ; Conotoxin GIIIA ; Sodium channels ; Veratridine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Conotoxin GIIIA and GIIIB from the marine snail Conus geographus have been reported to inhibit voltage-dependent Na channels in skeletal muscle and postganglionic sympathetic neuron, but have no effect on Na channels in brain, giant axon and heart. In eel electroplax, conotoxins were also shown to share the common binding sites with saxitoxin (see review Gray et al. 1988). In bovine adrenal medullary cells, conotoxin GIIIA inhibited veratridine-induced influx of 22Na, 45Ca and secretion of catecholamines with an IC50 of 6 μmol/l, while saxitoxin suppressed veratridine-induced responses with an IC50 of 6.3 nmol/l. [3H]Saxitoxin binding to the cells was inhibited by unlabeled saxitoxin with an IC50 of 5.1 nmol/l, but was slightly reduced by 10 μmol/l conotoxin GIIIA. Conotoxin GIIIA, at 10 μmol/l, did not alter carbachol-induced influx of 22Na, 45Ca and secretion of catecholamines as well as high K-induced 45Ca influx and catecholamine secretion. These results indicate that conotoxin GIIIA, at concentrations 950 fold higher than saxitoxin, inhibits Na influx via voltage-dependent Na channels, but has no effect on the nicotinic receptor-ion channel complex or the voltage-dependent Ca channels. Conotoxin GIIIA seems to bind at the sites which are distinct from saxitoxin, but are functionally linked to the voltage-dependent Na channels. Conotoxins may be useful for the classification of Na channels in excitable cell membranes.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00169444
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  • 6
    Digitale Medien
    Digitale Medien
    Stimulatory effects of brain natriuretic peptide on cyclic GMP accumulation and tyrosine hydroxylase activity in cultured bovine adrenal medullary cells (1991)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 343 (1991), S. 289-295 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Adrenal medulla ; Atrial natriuretic peptide ; Brain natriuretic peptide ; Cyclic GMP ; Tyrosine hydroxylase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We studied the effect of brain natriuretic peptide (BNP) on the accumulation of cyclic GMP and the phosphorylation and activity of tyrosine hydroxylase, compared with that of atrial natriuretic peptide (ANP), in cultured bovine adrenal medullary cells. 1. BNP as well as ANP increased cellular cyclic GMP accumulation in a concentration-dependent manner (10–1000 nmol/1). BNP (1 μmol/1) and ANP (1 μmol/1) produced a 60-fold and 30-fold increase in cyclic GMP accumulation, respectively. 2. The stimulatory effects of BNP and ANP on cyclic GMP accumulation were observed even when Ca2+ or Na+ was removed from the incubation medium. 3. 12-O-Tetradecanoylphorbol 13-acetate (TPA), an activator of protein kinase C, inhibited the stimulatory effect of BNP on cyclic GMP accumulation in a concentration-dependent manner (1–100 nmol/1). Furthermore, the BNP-induced accumulation of cyclic GMP was attenuated by forskolin (1 μmol/1), an activator of adenylate cyclase. 4. BNP (1 μmol/1) and ANP (1 μ mol/1) caused a significant increase in phosphorylation and activity of tyrosine hydroxylase in the cells. 5. In digitonin-permeabilized cells, cyclic GMP (1–100 μmol/1) activated tyrosine hydroxylase in the presence of ATP and Mg2+. These results suggest that BNP stimulates the accumulation of cyclic GMP in a manner similar to that of ANP. The increased accumulation of cyclic GMP by these peptides may be negatively modulated by protein kinase C and cyclic AMP and may cause the phosphorylation and activation of tyrosine hydroxylase-in cultured bovine adrenal medullary cells.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00251128
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  • 7
    Digitale Medien
    Digitale Medien
    Veratridine-induced phosphorylation and activation of tyrosine hydroxylase, and synthesis of catecholamines in cultured bovine adrenal medullary cells (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 339 (1989), S. 653-659 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Adrenal medulla ; Catecholamine synthesis ; Protein kinase C ; Tyrosine hydroxylase ; Veratridine
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary The mechanism of the synthesis of catecholamines by veratridine was studied in cultured bovine adrenal medullary cells. (1) Veratridine increased the phosphorylation and activity of tyrosine hydroxylase as well as the synthesis of [14C]catecholamines from [14C]tyrosine, all of which were inhibited by tetrodotoxin. Veratridine-induced activation of tyrosine hydroxylase and synthesis of [14C]catecholamines were reduced in 20 mmol/l extracellular Na+ or in Ca2+-free medium. (2) 12-O-Tetradecanoylphorbol-13-acetate (TPA), an activator of protein kinase C, increased the synthesis of [14C]catecholamines. In the presence of TPA, veratridine did not produce any additional increase in [14C]catecholamine synthesis. In protein kinase C-deficient cells which were prepared by pretreatment with 1 μ ol/1 TPA for 24 h, TPA failed to increase [14C]catecholamine synthesis and veratridine-induced [14C]catecholamine synthesis was suppressed by 50%. (3) Polymyxin B, an inhibitor of protein kinase C and N-(6-aminohexyl)-5-chloro-l-naphthalenesulfonamide (W-7), an inhibitor of calmodulin, inhibited veratridine-stimulated synthesis of [14C]catecholamines as well as veratridine-induced influx of 22Na+ and 45Ca2+ with similar potencies. (4) In digitonin-permeabilized cells, polymyxin B attenuated the activation of tyrosine hydroxylase caused by Ca2+. These results suggest that veratridine-induced synthesis of catecholamines and activation of tyrosine hydroxylase were mediated by Ca2+-dependent phosphorylation of this enzyme, and protein kinase C may be responsible, at least in part, for this process.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00168658
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  • 8
    Digitale Medien
    Digitale Medien
    Inhibition by vecuronium of carbachol-induced influx of22Na2+,45Ca2+ and secretion of catecholamines in cultured bovine adrenal medullary cells (1989)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 340 (1989), S. 605-609 
    Details
    ISSN: 1432-1912
    Schlagwort(e): Adrenal medulla ; Catecholamine secretion ; Nicotinic receptor-ion channel complex ; Sodium influx ; Vecuronium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary In cultured bovine adrenal medullary cells, vecuronium, pancuronium and D-tubocurarine reduced carbachol-induced45Ca2+ influx and catecholamine secretion by inhibiting22Na+ influx via nicotinic receptor-ion channel complex with IC50 values of 0.43, 7.6 and 3.9μmol/l, respectively. IC50 values of pancuronium and D-tubocurarine observed in adrenal medulla were one order of magnitude higher than the plasma concentrations of these muscle relaxants reported to produce 50% neuromuscular blockade, while IC50 of vecuronium was quite close between adrenal medulla and skeletal muscle.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00717734
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  • 9
    Digitale Medien
    Digitale Medien
    An active metabolite of carbamazepine, carbamazepine-10,11-epoxide, inhibits ion channel-mediated catecholamine secretion in cultured bovine adrenal medullary cells (1998)
    Springer
    Psychopharmacology 135 (1998), S. 368-373 
    Details
    ISSN: 1432-2072
    Schlagwort(e): Key words Carbamazepine-10 ; 11-epoxide ; Carbamazepine-10 ; 11-diol ; Catecholamine secretion ; Nicotinic acetylcholine receptor-associated ion channel ; Voltage-dependent Na+ channel ; N-type voltage-dependent Ca2+ channel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract  We have recently reported inhibitory effects of carbamazepine (CBZ) on ion channel-mediated secretion of catecholamines in bovine adrenal medullary cells. Here, we report the effects of carbamazepine-10,11-epoxide (CBZ-E), an active metabolite of CBZ, and carbamazepine-10,11-diol (CBZ-D), a non-active metabolite, on 22Na+ influx, 45Ca2+ influx and catecholamine secretion in cultured adrenal medullary cells. CBZ-E, but not CBZ-D inhibited 22Na+ influx, 45Ca2+ influx and catecholamine secretion induced by carbachol or veratridine with a half-maximal inhibitory concentration (IC50) of 0.26 or 0.68 μg/ml, respectively. CBZ-E also inhibited high K+-evoked 45Ca2+ influx and catecholamine secretion (IC50 = 0.3 μg/ml), but CBZ-D did not. These findings suggest that CBZ-E, but not CBZ-D, attenuates catecholamine secretion by inhibiting nicotinic acetylcholine receptor-associated ion channels, voltage-dependent Na+ channels and voltage-dependent Ca2+ channels in the cells. This inhibition of CBZ-E as well as CBZ may be related to the clinical effects in neuropsychiatric disorders.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s002130050524
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