A capacitative calcium current in cultured skeletal muscle cells is mediated by the calcium-specific leak channel and inhibited by dihydropyridine compounds. (49/56)

Calcium stores from cultured skeletal muscle cells were depleted using cyclopiazonic acid (CPA), a reversible inhibitor of Ca2+-ATPases at the sarcoplasmic reticulum. Store depletion led to activation of the calcium-specific leak channel, as assayed using single-channel patch clamp analysis and rates of manganese influx and quenching of fura-2 fluorescence. Two novel dihydropyridine compounds inhibited this single-channel leak channel activity, the resting and depletion-induced manganese influx, and refilling of the CPA-depleted intracellular calcium store. These compounds represent the first antagonists for a calcium leak channel and for a channel that mediates a capacitative current. The development of the skeletal muscle capacitative current was inhibited by genistein, a tyrosine kinase inhibitor, but was not affected by okadaic acid, a phosphatase inhibitor, or econazole. Thus, the capacitative current in cultured skeletal muscle cells was mediated by the calcium leak channel and was inhibited by pharmacological antagonists and may provide a model system for uncovering the complete set of signals leading from store depletion to channel activation.  (+info)

Functional effects of econazole on inducible nitric oxide synthase: production of a calmodulin-dependent enzyme. (50/56)

1. We performed experiments to examine the effects of an anti-fungal imidazole compound, econazole, on the regulation and effects of lipopolysaccharide-inducible nitric oxide synthase (iNOS) activity in rat aortic rings and cultured J774 murine macrophage cells. 2. In endothelium-intact rings of thoracic aorta, phenylephrine caused a concentration-dependent contraction with EC50 of 1.9 +/- 0.15 x 10(-8) M (n = 5). Following incubation with lipopolysaccharide (LPS, 5 micrograms ml-1) for 8 h there was a right-shift in the concentration-response curve (EC50 3.1 +/- 0.28 x 10(-7) M, P < 0.05) with a depression in the maximum contraction from 1.44 +/- 0.25 g to 0.86 +/- 0.26 g (n = 4). Co-incubation of rings with econazole (1 x 10(-5) M) partially inhibited the LPS-induced loss of reactivity to phenylephrine (EC50 6.5 +/- 0.72 x 10(-8) M) and fully inhibited the reduction in maximum tension (1.49 +/- 0.19 g; n = 5). 3. In J774 cells, incubation with LPS (10 micrograms ml-1, 24 h) resulted in significant nitrite production that was inhibited by co-incubation with econazole (IC50 5.0 +/- 0.9 x 10(-6) M; n = 5). In cells stimulated with LPS, production of L-[3H]-citrulline from L-[3H]-arginine was 6.41 +/- 0.22 pmol mg-1 protein min-1 (n = 3). This was inhibited by 92 +/- 6% by addition of NG-monomethyl-L-arginine (L-NMMA, 1 x 10(-3) M; n = 3) to the homogenate but not by econazole (1 x 10(-5) M; n = 3). In contrast pretreatment of cells with econazole (1 x 10(-5) M) markedly reduced the LPS-induced [3H]-citrulline production (0.86 +/- 0.053 pmol mg-1 protein min-1; P < 0.01; n = 3). 4. In cells treated with LPS and econazole, L-[3H]-citrulline production was restored in a concentration-dependent manner by addition of calmodulin (1 x 10(-8)-3 x 10(-7) M) with an IC50 of 4.2 +/- 0.9 x 10(-8) M. 5. We have shown that econazole inhibits the functional and biochemical activity of iNOS in rat aortic rings and cultured J774 cells. Treatment of cells with econazole renders the NO synthase functionally inactive. In econazole-treated cells enzyme activity is restored by calmodulin suggesting that econazole may inhibit the binding of this essential co-factor to the enzyme following its production. These studies may have implications for the design of novel anti-inflammatory agents working through the L-arginine-nitric oxide pathway.  (+info)

Extracellular site for econazole-mediated block of Ca2+ release-activated Ca2+ current (Icrac) in T lymphocytes. (51/56)

1. Standard whole cell patch clamp recording techniques were used to study the pharmacological characteristics and site of econazole-mediated inhibition of calcium release-activated calcium current (Icrac) in the human leukaemic T cell line, Jurkat. 2. Extracellularly applied econazole blocked Icrac in a concentration-dependent manner (IC50 approximately 14 microM). Block developed over a relatively slow timecourse of 30-60 s (10 microM), and only partially reversed over minutes. 3. Econazole dialysed from the pipette into the cytosol at concentrations ranging from 0.1 to 30 microM did not reduce Icrac, or quantitatively affect Icrac block by extracellularly applied econazole. 4. A less lipophilic quaternary iodide derivative of econazole was synthesized to retard absorption through the cell membrane. When applied extracellularly, this compound blocked Icrac in a concentration-dependent manner with onset kinetics comparable to econazole. 5. Results with intracellularly dialysed econazole and the quaternary econazole derivative provide convergent evidence that econazole blocks Icrac via an extracellular interaction. 6. The inability of intracellularly applied econazole to inhibit Icrac argues against the notion that econazole inhibits capacitative Ca2+ entry pathways secondary to its known inhibitory effects on cytochrome P-450.  (+info)

Rapid high performance liquid chromatographic assay for antifungal agents in human sera. (52/56)

Serum concentration of seven antifungal agents, amphotericin B, 5-flucytosine, ketoconazole, fluconazole, itraconazole, miconazole and econazole were assayed using a single step sample preparation and an isocratic High Performance Liquid Chromatography (HPLC) procedure based on three mobile phases of similar components. Our method was simple, flexible and rapid, the assays being completed within half an hour. The method showed high reproducibility, good sensitivity with detection limits of 0.078 to 0.625 mg/L except for miconazole and econazole, and high recovery rates of 86-l05%. Out of 24 therapeutic agents tested only aztreonam and trimethoprim were found to interfere with the assay of 5-flucytosine and fluconazole respectively, using this protocol. HPLC assay should be useful in the clinical laboratory for monitoring patients on antifungal therapy.  (+info)

Colcemid and econazole do not show aneugenicity in male mouse germ cells. (53/56)

Colcemid (COM) and econazole (EZ) were tested for induction of mitotic arrest and C-mitotic effects in mouse bone marrow cells and for meiotic delay and induction of hyperploidy in mouse spermatocytes after single injection. Doses of 1 and 3 mg/kg COM were used and bone marrow and spermatocytes were sampled at 2, 6, 10, 14 and 18 h. For EZ a dose of 120 mg/kg and intervals of 6, 10, 14 and 18 h were chosen. At 2 h after COM treatment of bone marrow cells the mitotic index and C-mitotic effect were highest, then both decreased from 6 to 18 h. At 18 h the mitotic indices decreased to or significantly below the control level at doses of 1 and 3 mg/kg respectively, whereas the corresponding frequencies of C-mitotic cells were still significantly higher than in the controls. EZ also induced mitotic arrest and C-mitotic effects in mouse bone marrow cells. In contrast to COM, the effects of EZ were highest at 18 h after treatment. COM and EZ caused disturbances in progression from the first to second meiotic division, however, after COM treatment the ratios of MMII to MMI were significantly below the control. In contrast, after EZ treatment the ratios were significantly higher than in the controls. Such differences may result from the different mechanisms by which COM and EZ act on cell cycle progression. COM and EZ did not induce non-disjunction under the experimental conditions. However, EZ induced structural chromosomal aberrations.  (+info)

Disk diffusion susceptibility testing of dermatophytes with imidazoles. (54/56)

In vitro susceptibility testing of 43 isolates of dermatophytes was carried out against imidazoles-ketoconazole, miconazole and econazole and griseofulvin by agar dilution and disk diffusion methods. Econazole was the most effective drug inhibiting all the isolates at a concentration of 0.1 microgram ml-1. The MIC 50s and MIC 90s for ketoconazole and miconazole were 1 and 2.5 mg ml-1 whereas the values for griseofulvin were 1 and 5 micrograms ml-1. Good correlation was seen between the MIC and sizes of zones of inhibition around the disks. Regression analysis was used to measure the degree of correlation between the MIC values and matched averaged zones of inhibition and the correlation coefficients for econazole, ketoconazole, miconazole and griseofulvin were -0.5554, -0.5886, -0.8558 and -0.8268 (p < 0.001) respectively.  (+info)

Control of Candida albicans murine vaginitis by topical administration of polycarbophil-econazole complex. (55/56)

The complexation of econazole with the mucoadhesive polycarbophil was found to significantly improve the therapeutic benefit of the drug in the topical treatment of experimental vaginal candidiasis in mice, while no difference in the antimycotic activity exerted by econazole and polycarbophil-econazole could be detected in vitro.  (+info)

Multiple effects of econazole on calcium signaling: depletion of thapsigargin-sensitive calcium store, activation of extracellular calcium influx, and inhibition of capacitative calcium entry. (56/56)

The effect of econazole on intracellular calcium levels ([Ca2+]i) in Madin Darby canine kidney cells was investigated using fura-2 fluorimetry. Econazole increased [Ca2+]i dose-dependently at 5-50 microM. The Ca2+ signal consisted of an initial rise, a gradual decay and a sustained plateau. Extracellular Ca2+ removal partially reduced the econazole response. Mn2+ quench of fura-2 fluorescence confirmed econazole-induced Ca2+ influx. The econazole-sensitive intracellular Ca2+ store overlaps with that sensitive to thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+ pump, because 25 microM econazole depleted the thapsigargin-sensitive store, and conversely, thapsigargin abolished the econazole response. Econazole (25-50 microM) partially inhibited capacitative Ca2+ entry induced by cyclopiazonic acid, another endoplasmic reticulum Ca2+ pump inhibitor, measured by depleting internal Ca2+ store in Ca(2+)-free medium followed by adding 10 mM CaCl2. Econazole induced capacitative Ca2+ entry itself. Pretreatment with La3+ (100 microM) partially inhibited 25 microM econazole-induced Mn2+ quench of fura-2 fluorescence, and La3+ immediately reduced 20 microM econazole-induced Ca2+ signal when added at the peak of the signal, suggesting that econazole induced Ca2+ influx via two separate pathways: one is sensitive to La3+, the other is not. La3+ enlarged 25 microM econazole-induced [Ca2+]i transient during the decay phase. The econazole response was not altered when the cytosolic level of inositol 1,4,5-trisphosphate was inhibited by the phospholipase C inhibitor U73122.  (+info)