Hypoxia, Free Radicals, and Reperfusion Injury Following Cold Storage and Reperfusion of Livers for Transplantation
John J. Lemasters, Constance Oliver in Cell Biology of Trauma, 2020
Frequently, cell killing by A23187, the calcium ionophore, is cited as an example of Ca2+-dependent cell killing.72 In hepatocytes, fructose alone does not protect against lethal cell injury caused by Br-A23187, a nonfluorescent analog of A23187; however, fructose in combination with oligomycin does offer protection.57 A23187 is a potent uncoupler of mitochondrial oxidative phosphorylation.73 Oligomycin, a specific inhibitor of the uncoupler-stimulated mitochondrial ATPase, is cytotoxic by itself. Protection by the combination of fructose and oligomycin suggests that cell killing by A23187 is mediated by mitochondrial uncoupling and consequent cellular ATP depletion, rather than by Ca2+ entry into hepatocytes per se. Fructose also protects against CCCP, a classical mitochondrial uncoupler, only when oligomycin is present.57,60
Membrane Properties of Peritoneal Macrophage
Richard C. Niemtzow in Transmembrane Potentials and Characteristics of Immune and Tumor Cell, 2020
To test this idea, the effects of application of the ionophore have been compared to the natural changes that take place when the macrophages are activated by antigenic stimulation. The effects of cholera toxin, which is an activator of cyclic nucleotide production in some preparations,34 and isomethylbutylxanthine (IBMX), an inhibitor of phosphodiesterase activity, have also been examined in macrophage. The results of these agents on the membrane potentials of activated and nonactivated macrophage is given in Table 2. The alternative criteria that has been used to test the effect of the activating agents has been to examine changes in respiration. Activated macrophage have characteristically higher respiration rates than macrophage measured prior to antigenic stimulation. When the respiration of activated macrophage is compared with the respiration of nonactivated cells before and after the application of A23187 and cholera toxin. There is a substantial increase in respiration of the nonactivated cells. For A23187, the respiration of activated and nonactivated cells becomes virtually identical.
Abnormalities of the Calcium Pump in Primary Hypertension
Antonio Coca, Ricardo P. Garay in Ionic Transport in Hypertension: New Perspectives, 2019
Dagher et al.63 developed a new method in 1987 for the study of the kinetic properties of the Ca2+-dependent ATPase in intact RBC. The erythrocytes were exposed to the presence of the A23187 ionophore, which increases the passive permeability of the cell membrane for divalent cations and promotes the intracellular accumulation of Ca2+. The addition of cobalt chloride to the medium immediately blocks all movements of calcium due to the A23187 ionophore, without affecting the active extrusion of calcium through the pump. The application of this methodology to the study of laboratory hypertension was not able to show significant differences in calcium affinity or maximal transport rate in SHR, as can be seen in Table 1.
A retrospective analysis of artificial oocyte activation in patients with low or no fertilisation in intracytoplasmic sperm injection cycles
Published in Journal of Obstetrics and Gynaecology, 2022
Kevin K. W. Lam, Jacki Y. Y. Wong, Tak-Ming Cheung, Raymond H. W. Li, Ernest H. Y. Ng, William S. B. Yeung
Calcium ionophores are lipid soluble molecules. They transport calcium ions across the cell membrane which in turn induce a single transient rise in intracellular calcium level. When used for AOA, the concentration of A23187 varies from 5–10 µM (Montag et al. 2012; Lv et al. 2020). Although the concentration of the ready-to-use A23187 reagent is not disclosed by the manufacturer, it has been shown to induce a single rise in intracellular calcium to a peak within two minutes (Nikiforaki et al. 2016). The safety and efficacy of the ready-to-use A23187 has been proven in previous studies (Ebner et al. 2012; Caglar et al. 2015; Ebner et al. 2015). Exposure of A23187 in conjunction with calcium chloride injection together with spermatozoon has also been reported (Vanden Meerschaut et al. 2012). Our data indicated that the performance of two protocols were comparable. The observation is understandable as the injection of calcium chloride and the subsequent A23187 exposure might increase the intracellular calcium concentration to a level higher than that using A23187 alone, both protocols could not generate calcium oscillations (Nikiforaki et al. 2016). To the best of our knowledge, there is no commercially available mouse embryo-tested calcium chloride for AOA. The calcium chloride solution was mainly prepared from research grade chemicals (Vanden Meerschaut et al. 2012; Nikiforaki et al. 2016), the safety of which is in doubt. Based on the current data, AOA should be performed without the concomitant injection of calcium chloride.
Cellular Calcium Signals in Cancer Chemoprevention and Chemotherapy by Phytochemicals
Published in Nutrition and Cancer, 2022
Xue Li, Shuhan Miao, Feng Li, Fen Ye, Guang Yue, Rongzhu Lu, Haijun Shen, Yang Ye
DIM is a bioactive compound derived from indole-3-carbinol present in cruciferous vegetables such as cabbage, broccoli and cauliflower (122–126). DIM possesses prominent anticancer activity against different types of cancer including gastric cancer (123), breast cancer (127), colorectal cancer (128), hepatocellular carcinoma (129), prostate cancer (130, 131) and ovarian cancer (132). DIM also regulates calcium signals to inhibit cancer progression. Lu et al. reported that DIM induced MG63 human osteosarcoma cell apoptosis mainly by altering Ca2+ signals. Studies also found that DIM may raise cytosolic Ca2+ levels through inducing Ca2+ influx mediated by SOCE and Ca2+ release from ER calcium stores in a PLC-dependent manner (132). Additional studies demonstrated that DIM may regulate cytosolic Ca2+–mediated p38 MAPK activation to induce apoptosis in human hepatocellular carcinoma cells. Moreover, A23187, a calcium ionophore, enhanced DIM-induced cell death (129).
Assisted oocyte activation with calcium ionophore 44 hours after intracytoplasmic sperm injection resulting in successful pregnancy
Published in Gynecological Endocrinology, 2020
Haitao Xi, Yanghua Fu, Chang Liu, Xiaosheng Lu, Liucai Sui, Yulu Chen, Junzhao Zhao
During in vitro fertilization, both sperm and ovum need to undergo the process of capacitation. Sperm capacitation could be operated by using A23187 calcium solution or heparin. Calcium ionophore A23187 is a kind of mobile ionophore, which could transport bivalent cation such as calcium ion or magnesium ion into the cells and take two hydrogen ions outside the cells simultaneously. When A23187 is added to the culture medium containing calcium ion, the calcium ion could enter into the cytoplasm quickly. Thus, A23187 is widely used in cell biological research to increase the concentration of free calcium in the cytoplasm.
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