[The effect of cyclooxygenase and lipoxygenase inhibitors on Ca(2+)-responses induced by glutoxim and molixan in macrophages]

Glutoxim and molixan belong to a new generation of disulfide-containing drugs with immunomodulatory, hepatoprotective and hemopoetic effect. Using Fura-2AM microfluorimetry, the possible involvement of the cyclooxygenase and lipoxygenase pathways of arachidonic acid oxidation in the effect of glutoxim and molixan on the intracellular Ca2+ concentration in rat peritoneal macrophages has been investigated. We have shown for the first time that preincubation of the cells with the cyclooxygenase inhibitors, indomethacin and aspirin, or lipoxygenase inhibitors, nordihydroguaiaretic acid, caffeic acid and baicalein, almost completely prevents the intracellular Ca2+ concentration increase induced by glutoxim or molixan. The obtained data indicate the involvement of products and/or enzymes of the arachidonic acid cyclooxygenase and lipoxygenase metabolism pathways in the effect of glutoxim and molixan on the processes of Ca2+ signaling in macrophages.

[The involvement of actin cytoskeleton in glutoxim and molixan effect on intracellular Ca(2+)-concentration in macrophages]

Glutoxim and molixan belong to new generation of disulfide-containing drugs with immunomodulatory, hepatoprotective and hemopoetic effect on cells. Using Fura-2AM microfluorimetry, two structurally distinct actin filament disrupters, latrunculin B and cytochalasin D, and calyculin A, which causes actin filaments condensation under plasmalemma, we have shown the involvement of actin cytoskeleton in the intracellular Ca(2+)-concentration increase induced by glutoxim or molixan in rat peritoneal macrophages. Morphological data obtained with the use of rhodamine-phalloidine have demonstrated that glutoxim and molixan cause the actin cytoskeleton reorganization in rat peritoneal macrophages.

[Superfamily of voltage dependent K+ channels: structure, functions and pathology]

In this review the recent studies related to the voltage dependent K+ channels are discussed. During the last 15 years the molecular cloning revealed a large number of alpha-subunits of voltage dependent K+ channels. This approach enabled to elucidate the properties of different types of channels and, in particular, characteristics of such structural elements as auxiliary subunits. These subunits are mainly responsible for the ionic permeability features of alpha-subunits. There are several cytoplasmic and membrane-associated auxiliary subunits such as beta-subunits, minK (minimal K+ channel peptide), MiRP (minK-related peptide), KChAP (K+ channel-associated protein), KChIP (K+ channel-interacting protein) and NCS (neuronal calcium sensor).

[The effect of oxidized glutathione and its pharmacological analogue, glutoxim, on intracellular Ca2+ concentration in macrophages]

The effect of oxidized glutathione (GSSG) and its pharmacological analogue, glutoxim, on intracellular Ca2+ concentration in rat peritoneal macrophages was investigated using Fura-2AM microfluorimetry. It was shown that both GSSG and glutoxim increased intracellular Ca2+ concentration inducing Ca(2+)-mobilization from thapsigargin-sensitive Ca(2+)-stores and subsequent Ca2+ entry into macrophages from external medium. Dithiothreitol, which reduces S-S-bonds in proteins, completely prevented or reversed the increase in the intracellular Ca2+ concentration induced by GSSG or glutoxim. It suggests that the increase in the intracellular Ca2+ concentration induced by GSSG or glutoxim can be mediated by their interactions with functionally important SH-groups of proteins involved in Ca(2+)-signaling. Two structurally different tyrosine kinase inhibitors, genistein and methyl-2,5-dihydroxycinnamate, prevented or completely reversed the increase in the intracellular Ca(2+)-concentration induced by GSSG or glutoxim. On the contrary, tyrosine phosphatase inhibitor, Na orthovanadate, enhanced the increase in the intracellular Ca2+ concentration evoked by oxidizing agents. The data suggest that tyrosine kinases and tyrosine phosphatases are involved in regulatory effects of GSSG and glutoxim on the intracellular Ca2+ concentration in macrophages.

[The effect of phosphatidylinositol kinase inhibitors on store-dependent Ca2(+)-transport in macrophages]

Using Fura-2AM microfluorimetry the role of phosphatidylinositol kinases in the regulation of Ca2+ signals induced by purinergic agonist ATP and endoplasmic Ca2(+)-ATPase inhibitor thapsigargin in rat peritoneal macrophages was investigated. It was shown that two structurally distinct phosphatidylinositol 3- and phosphatidylinositol-4-kinases inhibitors wortmannin and LY294002 showed a dose- dependent effect on store-dependent Ca2(+)-entry, induced by thapsigargin or ATP. The data suggest that phosphatidylinositol 3- and phosphatidylinositol-4-kinases play an important role in the activation of store-dependent Ca2(+)-entry in macrophages and that their effect might be mediated by their influence on actin cytoskeleton. The results are compatible with the "secretion-like coupling model" for store-dependent Ca2(+)-entry in macrophages based on a reversible trafficking and coupling of the Ca2+ store with the plasma membrane which suggests the involvement of microfilaments and phosphatidylinositol kinases.

[Effect of latrunculin B, jasplakinolide and brefeldin A on the store-dependent Ca2+ entry in macrophages]

Using Fura-2AM microfluorimetry, effect of actin filament modifiers and vesicular trafficking inhibitor on the store-dependent Ca2+ entry induced by purinergic agonists (ATP, UTP) and endoplasmic Ca2+-ATPase inhibitors (thapsigargin, cyclopiazonic acid) in rat peritoneal macrophages was investigated. It was shown that inhibition of actin polymerization by latrunculin B had a biphasic time-dependent effect on Ca2+ entry, showing an initial potentiation followed by inhibition of Ca2+ entry. Moreover, addition of latrunculin B after induction of store-dependent Ca2+ entry inhibited the Ca2+ influx. Jasplakinolide, which reorganizes actin filaments into a tight cortical layer adjacent to the plasma membrane, prevented activation of store-dependent Ca2+ entry but did not modify this process after its activation. Vesicular transport inhibitor brefeldin A, which inactivates arfproteins, inhibited activation of store-dependent Ca2+ entry but did not alter this mechanism once being initiated. These data are compatible with the sectretion-like coupling model for store-dependent Ca2+ entry in macrophages based on a reversible trafficking and coupling of Ca2+ store with the plasma membrane.

[Effect of arachidonic and other fatty acids on the intracellular calcium concentration and calcium signaling in peritoneal macrophages]

Effects of arachidonic and other fatty acids on the intracellular Ca2+ concentration ([Ca2+]i) in rat peritoneal macrophages was investigated. It has been shown that cis-polyunsaturated arachidonic and linoleic induce a significant and dose-dependent increase in [Ca2+]i, which is due to depletion of thapsigargin-sensitive Ca2+ store and to stimulation of Ca2+ entry from the extracellular medium. Pharmacological characteristics of Ca2+ entry induced by arachidonic acid appeared to be similar to those of store-dependent Ca2+ entry activated by thapsigargin or cyclopiazonic acid; Ca2+ entry is attenuated by the same Ca2+ channel inhibitors, by tyrosine kinase inhibitor genistein and epoxygenase inhibitor proadifen. Cis-monounsaturated oleic and saturated myristic acids appeared to be less effective and induced only a slight increase in [Ca2+]i at much higher concentrations. Arachidonic and other fatty acids can also stimulate Ca(2+)-ATPase in the macrophage plasma membrane. The data are compatible with the important role played by arachidonic and other free fatty acids in the regulation of [Ca2+]i in peritoneal macrophages.

[The role of cytoskeleton structures in regulation of Ca2+ responses in macrophages]

The role of the cytoskeleton in regulation of purinergic agonist- and endoplasmic Ca(2+)-ATPase inhibitors-induced Ca2+ signals in rat peritoneal macrophages was investigated. It has been shown that in cells pretreated with agents that disrupt microtubules (vinblastine, colchicine, colcemid) or actin microfilaments (cytochalasins, phalloidin), the ability of thapsigargin or cyclopiazonic acid to empty Ca2+ stores and activate store-dependent Ca2+ influx was significantly attenuated. On the contrary, microfilaments and microtubule disrupters did not affect ATP- or UTP-induced Ca2+ mobilization, indicating that release of Ca2+ from intracellular stores through the inositol phosphate pathway was intact. The results suggested that an intact cytoskeleton is required for capacitative Ca2+ entry but not for agonist-induced Ca2+ mobilization.