The role of reactive oxygen species in membrane potential changes in macrophages and astrocytes.

Involvement of reactive oxygen species (ROS) in changes of the plasma membrane potential of mouse peritoneal macrophages and astrocytes (U118 cell line) under the action of different agents has been studied. Membrane potential was measured using the voltage-dependent fluorescent oxonol dye DiBAC4(3). Agonists which stimulate macrophages to release ROS (the fMLP peptide and platelet activating factor) caused prolonged hyperpolarization. Experiments with the fluorescent probe 2',7'-dichlorofluorescein diacetate have shown that astrocytes release ROS upon the action of C5a complement anaphylatoxin (but not C3a). The effect of C5a was accompanied with hyperpolarization of the astrocyte plasma membrane. Treatment of the cells with agents which do not induce ROS generation (C3a, lipopolysaccharide, interferon-gamma) depolarized the plasma membrane. Hyperpolarization of both cell types was significantly decreased in the presence of superoxide dismutase (but not catalase). Moreover, the O2- -generating system caused a marked hyperpolarization of both cell types. The data obtained suggest that O2- is involved in the macrophage and astrocyte hyperpolarization response.

[Activation of astrocytes of by anaphylatoxins of the complement system]. / Aktivatsiia astrotsitov anafilatoksinami sistemy komplementa.

It has been shown that astrocytes (human glioblastoma U118 cell line) release reactive oxygen species (ROS), including superoxide O2.- and hydrogen peroxide H2O2 following the action of C5a complement component C5a (but not C3a). The effect of C5a (1 nM) is accompanied with hyperpolarization of the astrocyte plasma membrane. Component C3a (100 nM), which is not an inducer of ROS, caused a prolonged depolarization of astrocytes. However, both the agents induced a transient increase in intracellular Ca2+ concentration. The data obtained permit a conclusion that O2.- participates in the intracellular signal transduction, and is involved in the mechanism of hyperpolarization response of astrocytes to the effect of the inducer of ROS, complement component C5a.

[Mechanisms of hyperpolarization of plasma membrane of macrophages and astrocytes during activation]. / Mekhanizm giperpoliarizatsii plazmaticheskoi membrany makrofagov i astrotsitov pri aktivatsii.

The hyperpolarization response of macrophages and glial cells (astrocytes, U118 cell line) to the action of inducers of reactive oxygen species (ROS) has been studied. Macrophages were stimulated with chemotactic peptide fMLP and platelet activation factor (PAF). Astrocytes were affected by complement component--anaphylatoxin C5a. The hyperpolarization response of both cell types depends on intracellular Ca2+ concentration and extracellular K+ concentration. Depletion of K+ concentration in the medium (1 mM KCl) or chelation of intracellular Ca2+ with Quin-2 (50 microM) significantly decreased the hyperpolarization response or caused depolarization of plasma membrane. Moreover, inhibition of Ca(2+)-dependent K(+)-channels with quinidine (50 microM) induced only a prolonged depolarization of both cell types. The data obtained permit a suggestion that macrophage and astrocyte hyperpolarization response to stimulation with ROS inducers involves O2.- mediated activation of Ca(2+)-dependent K(+)-channels.

[Modification of biochemical changes in developing cultures of chick embryo nerve tissue cultures]. / Modifikatsiia ékzogennymi gangliozidami biokhimicheskikh izmenenii v razvivaiushcheisia kul'ture nervnoi tkani kurinogo émbriona.

The effects of exogenous ganglioside GM1 (1 microM) from bovine brain on the morphological state and biochemical parameters (creatine kinase, acetylcholinesterase and adenylate cyclase activities as well as the protein, phospholipid and ganglioside content) have been studied in primary cultures of trypsin-treated dissociated cells of chicken embryonic brain. Ganglioside GM1 accelerated the growth and differentiation of cultured cells, increased the phospho- and glycolipid content and stimulated the activity of the enzymes.