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Cholangiocyte Ion Channels:
Published in Gianfranco Alpini, Domenico Alvaro, Marco Marzioni, Gene LeSage, Nicholas LaRusso, The Pathophysiology of Biliary Epithelia, 2020
Finally, it is important to emphasize that channel-mediated ion transport is dictated by transmembrane electrochemical gradients. Once the pore is revealed, ion movement is a passive process. For example, opening of a K+ -selective channel is followed by movement of ions out of the cell because the chemical gradient favoring efflux (from intracellular concentrations of ~140 mM to extracellular concentrations of ~4 mM) is greater than the interior negative membrane potential ~−50 mV).
Role of Cell-to-Cell Coupling in Control of Myometrial Contractility and Labor
Published in Robert E. Garfield, Thomas N. Tabb, Control of Uterine Contractility, 2019
The ability of myometrial cells to contract depends upon their ability to maintain ionic gradients across their plasma membranes (see Kao44). The ionic distribution in uterine smooth muscle, as in other excitable tissues, is such that sodium and calcium ions are higher outside the cell than inside, whereas potassium ions are higher within the cells. These ionic gradients allow the muscle cells to respond when small changes in permeability result in significant movements of ions down their electrochemical gradients.
Role of Carnosic Acid in Protection of Brain Mitochondria
Published in Shamim I. Ahmad, Handbook of Mitochondrial Dysfunction, 2019
In the mitochondria-related field, Sorbi et al. (1983) have found decreased pyruvate dehydrogenase complex (PDHC) activity in the brain of patients with AD [122]. Sheu et al. (1985) confirmed this information by performing an immunochemical study in the brain of AD patients [123]. Sheu et al. (1994) also observed abnormalities in the α-ketoglutarate dehydrogenase complex (α-KGDHC) in the fibroblasts obtained from subjects affected by familial AD [124]. Alterations in the activities of enzymes of the Krebs cycle and of the respiratory chain (mainly complex IV) were observed by different research groups and clearly indicate mitochondria-related bioenergetics deficits in the brain of those patients [125–128]. PDHC is an important link between the glycolysis and the Krebs cycle by producing acetyl-CoA from pyruvate, and α-KGDHC is part of the Krebs cycle, generating succinyl-CoA from α-ketoglutarate [129]. The α-KGDHC produces NADH + H+ by reducing NAD+, and NADH is a source of electrons to the complex I (NADH dehydrogenase) in the IMM. Therefore, important sources of the electrons that would be utilized to generate an electrochemical gradient across the IMM are affected in the brain of subjects suffering from AD.
Vacancy-induced toxicity of CoSe2 nanomaterials in rat lung macrophages
Published in Nanotoxicology, 2020
Guizhu Wu, Xue Chen, Ze Zhang, Nali Zhu, Qilin Yu, Huajie Liu, Lu Liu
Mitochondria play the important role in generating the large quantities of energy in the form of ATP and mediating the cell growth. One of the early intracellular events is the disruption of electrochemical gradient across the mitochondrial transmembrane, following the cell apoptosis. Thus, we measured the MMP by using the JC-1 dye. JC-1 aggregates which accumulated in mitochondria exhibited red fluorescence, while JC-1 monomer exhibiting green fluorescence cannot be accumulated in mitochondria. The decreased MMP would be indicated by increased green/red fluorescence and the obvious change was also regarded as the event of dysfunction of mitochondria and early apoptosis. The obtained green/red fluorescence revealed that N-CoSe2 induced more damage to mitochondria than P-CoSe2. The expression of cytochrome C released from mitochondria to cytoplasm and the level of ATP could also reinforce the above conclusion. What’s more, more downregulated genes related to ATP in N-CoSe2 than P-CoSe2 suggested the severe mitochondria damage caused by N-CoSe2 while no obvious damage induced in P-CoSe2. The result was also in accordance with the recent study that the abnormal ATP synthesis might affect the normal cellular activities, even lead to the cell apoptosis (Huang et al. 2019).
Toxicological profile of lipid-based nanostructures: are they considered as completely safe nanocarriers?
Published in Critical Reviews in Toxicology, 2020
Asaad Azarnezhad, Hadi Samadian, Mehdi Jaymand, Mahsa Sobhani, Amirhossein Ahmadi
Transmission through the CM is either passive or active. In the passive transport, an ion or molecule moves in the direction of the electrochemical gradient or its concentration. This type of transfer is performed without the assistance of energy (ATP) and is occurred in two ways: simple and facilitated diffusion. However, the active transport uses energy to transfer ion or molecule against the concentration of electrochemical gradient (Murphy 2009; Singh et al. 2009). Polar or charged biomolecules that cannot pass through the hydrophobic plasma membrane are internalized by a form of active transport which is called endocytosis. Broadly speaking, the internalization routs can be classified as nonspecific pathways including: (i) pinocytosis (cellular drinking that involve small pinocytic vesicles (≈100 nm)) or (ii) macropinocytosis involving large vacuole formation (0.2–0.5 μm), as well as specific pathways such as (iii) clathrin- or caveolin-mediated endocytosis (the protein-coat-driven route) or (iv) phagocytosis of objects larger than 0.5 μm by specialized phagocytes (Tan et al. 2019).
Strobilurin fungicide kresoxim-methyl effects on a cancerous neural cell line: oxidant/antioxidant responses and in vitro migration
Published in Toxicology Mechanisms and Methods, 2018
Evangelia Flampouri, Dimitra Theodosi-Palimeri, Spyridon Kintzios
ROS generation elicits free-radical attacks on phospholipids, followed by loss of mitochondrial membrane potential with the opening of the permeability transition pore (PTP), resulting in the release of intermembrane proteins to the cytosol (Cai 2005). In our study, the higher two applied KM concentrations significantly induced mitochondrial membrane depolarization in N2a cells (Figure 2(C)). In the mitochondrial matrix space, the energy released from the electron movement through the respiratory complexes is used to pump H+ out of the matrix. This electrochemical gradient can be assessed by ΔΨm sensitive probes (Ohtake et al. 1997). Since KM disrupts electron flow, loss of the mitochondrial membrane potential could also be associated, besides ROS attacks on membrane phospholipids, with perturbation of the proton gradient across the inner mitochondrial membrane. Similar to our results, mitochondrial membrane depolarization after KM exposure has recently been reported in primary cortical neurons (Regueiro et al. 2015). Results on human skin keratinocytes (HaCaT) treated with trifloxystrobin, another cytochrome bc1 inhibitor of the strobilurin family, also reveal altered mitochondrial membrane potential (Jang et al. 2016), while H9c2 cardiomyocites treated with the strobilurin fungicide azoxystrobin, showed collapsed transmembrane mitochondrial potential with a dose-dependent increase in mitochondrial superoxide anion generation (Rodrigues et al. 2015).