Search results for "Membrane potential"
showing 10 items of 327 documents
A secondary mode of action of the herbicide lenacil: Modification of K+ permeability of Acer pseudoplatanus cells
1984
Abstract The action of lenacil on plasmalemma permeability to K+, transmembrane electric potential difference (PD) calculated from the tetraphenylphosphonium distribution, proton extrusion and intracellular pH of Acer pseudoplatanus cells calculated from the 5,5-dimethyloxazolidine,4-dione distribution, was studied and compared with the action of fusicoccin (FC) and diethylstilbestrol (DES). The three compounds temporarily stimulated the rate of 86Rb+ uptake with a half-maximum effect at 5.0 μM for 3-cyclohexyl-6, 7-dihdro-1H-cyclopentapyrimidine-2,4(3H,5H)-dione (lenacil). Lenacil and FC had no action on transmembrane electric potential difference, whereas DES decreased it. Lenacil inhibit…
Magnesium ions promote assembly of channel-like structures from beticolin 0, a non-peptide fungal toxin purified from Cercospora beticola.
1998
Beticolins are toxins produced by the fungus Cercospora beticola. Using beticolin 0 (B0), we have produced a strong and Mg(2+)-dependent increase in the membrane conductance of Arabidopsis protoplasts and Xenopus oocytes. In protein-free artificial bilayers, discrete deflexions of current were observed (12 pS unitary conductance in symmetrical 100 mM KCl) in the presence of B0 (approximately 10 microM) and in the presence of nominal Mg2+. Addition of 50 microM Mg2+ induced a macroscopic current which could be reversed to single channel current by chelating Mg2+ with EDTA. Both unitary and macroscopic currents were ohmic. The increase in conductance of biological membranes triggered by B0 is…
Cercospora beticola toxins. Use of fluorescent cyanine dye to study their effects on tobacco cell suspensions
1996
Abstract The fluorescent dye 3,3′-diethylthiadicarbocyanine iodide [diS-C 2 -(5)] was used to observe plasmalemma transmembrane potential variations of tobacco cells treated with uncoupler (FCCP), respiratory inhibitors (azide and cyanide), and H + -ATPase inhibitors (DCCD and a carbanilate derivative). These chemicals induced an increase in fluorescence, indicating a dissipation of the transmembrane potential. The [diS-C 2 -(5)] was also used to study the effects of two Cercospora beticola toxins on tobacco cells. Changes in fluorescence of [diS-C 2 -(5)] suggested that these two toxins caused a dissipation of the transmembrane potential with a different magnitude whereas kinetics of their…
Inhibition of adenosine trephosphatase activity from a plasma membrane fraction of acer pseudoplatanus cells by 2,2,2-trichloroethyl 3,4-dichlorocarb…
1986
2,2,2-Trichloroethyl 3,4-dichlorocarbanilate (SW26) is toxic for Acer pseudoplatanus cell cultures. It inhibited the cellular proton extrusion and depolarized the plasmalemma. In vitro, it inhibited the plasma membrane ATPase. SW 26 was also inhibitory to membrane ATPases of other origins-plant (maize shoot), fungus (Schizosaccharomyces pombe), and animal (dog kidney)-with about the same efficiency (7.5 micromolar < I(50) < 22 micromolar). It did not inhibit the oligomycin-sensitive ATPase from purified plant mitochondria, nor molybdate-sensitive soluble phosphatases. SW26 was more specific for plasma membrane ATPases than diethylstilbestrol or vanadate. A Lineweaver-Burk plot analysis show…
The Plant Inorganic Pyrophosphatase Does Not Transport K+ in Vacuole Membrane Vesicles Multilabeled with Fluorescent Probes for H+, K+, and Membrane …
1995
Abstract It has been claimed that the inorganic pyrophosphatase (PPase) of the plant vacuolar membrane transports K+ in addition to H+ in intact vacuoles (Davies, J. M., Poole, R. J., Rea, P. A., and Sanders, D.(1992) Proc. Natl. Acad. Sci. U. S. A. 89, 11701-11705). Since this was not confirmed using the purified and reconstituted PPase consisting of a 75-kDa polypeptide (Sato, M. H., Kasahara, M., Ishii, N., Homareda, H., Matsui, H., and Yoshida, M. (1994) J. Biol. Chem. 269, 6725-6728), these authors proposed that K+ transport by the PPase is dependent on its association with other membrane components lost during purification. We have examined the hypothesis of K+ translocation by the PP…
Obesity impairs leukocyte‐endothelium cell interactions and oxidative stress in humans
2018
Background:To evaluate the relationship between leukocyte‐endothelial cellinteractions and oxidative stress parameters in non‐diabetic patients with differentgrades of obesity.Material and methods:For this cross‐sectional study, 225 subjects wererecruited from January 1, 2014 to December 31, 2016 and divided into groupsaccording to BMI (40 kg/m²). We determined clin-ical parameters, systemic inflammatory markers, soluble cellular adhesion mole-cules, leukocyte‐endothelium cell interactions—rolling flux, velocity and adhesion—, oxidative stress parameters—total ROS, total superoxide, glutathione—andmitochondrial membrane potential in leukocytes.Results:We verified that HOMA‐IR and hsCRP incr…
Zinc oxide nanoparticles mediated cytotoxicity, mitochondrial membrane potential and level of antioxidants in presence of melatonin.
2017
Zinc oxide nanoparticles (ZnO NPs) are widely used in a variety of products and are currently being investigated for biomedical applications. However, they have the potential to interact with macromolecules like proteins, lipids and DNA within the cells which makes the safe biomedical application difficult. The toxicity of the ZnO NP is mainly attributed reactive oxygen species (ROS) generation. Different strategies like iron doping, polymer coating and external supply of antioxidants have been evaluated to minimize the toxic potential of ZnO NPs. Melatonin is a hormone secreted by the pineal gland with great antioxidant properties. The melatonin is known to protect cells from ROS inducing …
Redox Imbalance and Mitochondrial Release of Apoptogenic Factors at the Forefront of the Antitumor Action of Mango Peel Extract
2021
Today, an improved understanding of cancer cell response to cellular stress has become more necessary. Indeed, targeting the intracellular pro-oxidant/antioxidant balance triggering the tumor commitment to cell demise could represent an advantageous strategy to develop cancer-tailored therapies. In this scenario, the present study shows how the peel extract of mango—a tropical fruit rich in phytochemicals with nutraceutical properties—can affect the cell viability of three colon cancer cell lines (HT29, Caco-2 and HCT116), inducing an imbalance of cellular redox responses. By using hydro-alcoholic mango peel extract (MPE), we observed a consistent decline in thiol group content, which was a…
PPAR gamma agonist leriglitazone improves frataxin-loss impairments in cellular and animal models of Friedreich Ataxia
2020
Friedreich ataxia (FRDA), the most common autosomal recessive ataxia, is characterized by degeneration of the large sensory neurons and spinocerebellar tracts, cardiomyopathy, and increased incidence in diabetes. The underlying pathophysiological mechanism of FRDA, driven by a significantly decreased expression of frataxin (FXN), involves increased oxidative stress, reduced activity of enzymes containing iron‑sulfur clus-ters (ISC), defective energy production, calcium dyshomeostasis, and impaired mitochondrial biogenesis, leading to mitochondrial dysfunction. The peroxisome proliferator-activated receptor gamma (PPARγ) is a ligand-activated transcriptional factor playing a key role in mito…
The role of Plasma Membrane Calcium ATPases (PMCAs) in neurodegenerative disorders
2017
Selective degeneration of differentiated neurons in the brain is the unifying feature of neurodegenerative disorders such as Parkinson's disease (PD) or Alzheimer's disease (AD). A broad spectrum of evidence indicates that initially subtle, but temporally early calcium dysregulation may be central to the selective neuronal vulnerability observed in these slowly progressing, chronic disorders. Moreover, it has long been evident that excitotoxicity and its major toxic effector mechanism, neuronal calcium overload, play a decisive role in the propagation of secondary neuronal death after acute brain injury from trauma or ischemia. Under physiological conditions, neuronal calcium homeostasis is…