Elevation of resting mitochondrial membrane potential of neural cells by cyclosporin A, BAPTA-AM, and Bcl-2

• Published in: American Journal of Physiology: Cell Physiology Vol. 279; no. 3; pp. C852 - C859
• Main Authors: Kowaltowski, Alicia J, Smaili, Soraya S, Russell, James T, Fiskum, Gary
• Format: Journal Article
• Language: English
• Published: United States 01.09.2000
• Subjects: Animals; Chelating Agents - pharmacology; Cyclosporine - pharmacology; Egtazic Acid - analogs & derivatives; Egtazic Acid - pharmacology; Humans; Hypothalamus - cytology; Hypothalamus - physiology; Intracellular Membranes - drug effects; Intracellular Membranes - metabolism; Membrane Potentials - drug effects; Mitochondria - drug effects; Mitochondria - physiology; Neurons - physiology; PC12 Cells; Permeability - drug effects; Proto-Oncogene Proteins c-bcl-2 - physiology; Rats; tert-Butylhydroperoxide - pharmacology; Tumor Cells, Cultured
• DOI: 10.1152/ajpcell.2000.279.3.C852
• ISSN: 0363-6143

1  Department of Anesthesiology, The University of Maryland Baltimore, Baltimore, Maryland 21201; 2  Departamento de Patologia Clínica, Faculdade de Ciências Médicas, Universidade Estadual de Campinas, Campinas, SP, Brazil; 3  Section on Neuronal Secretory Systems, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892; and 4  Departamento de Farmacologia, Universidade Federal de São Paulo, UNIFESP, São Paulo, Brazil This study tested the hypothesis that the activity of the mitochondrial membrane permeability transition pore (PTP) affects the resting mitochondrial membrane potential ( ) of normal, healthy cells and that the anti-apoptotic gene product Bcl-2 inhibits the basal activity of the PTP. was measured by both fluorometric and nonfluorometric methods with SY5Y human neuroblastoma cells and with GT1-7 hypothalamic cells and PC12 pheochromocytoma cells in the absence and presence of Bcl-2 gene overexpression. The resting of Bcl-2 nonexpressing PC12 and wild-type SY5Y cells was increased significantly by the presence of the PTP inhibitor cyclosporin A (CsA) or by intracellular Ca 2+ chelation through exposure to the acetoxymethyl ester of 1,2-bis(2-aminophenoxy)ethane- N,N,N',N' -tetraacetic acid (BAPTA-AM). The of Bcl-2-overexpressing PC12 cells was larger than that of Bcl-2-negative cells and not significantly increased by CsA or by Ca 2+ chelation. CsA did not present a significant effect on the monitored in unstressed GT1-7 cells but did inhibit the decrease in elicited by the addition of t -butyl hydroperoxide, an oxidative inducer of the mitochondrial permeability transition. These results support the hypothesis that an endogenous PTP activity can contribute to lowering the basal of some cells and that Bcl-2 can regulate the endogenous activity of the mitochondrial PTP. calcium; mitochondrial permeability transition; energy metabolism * A. J. Kowaltowski and S. S. Smaili contributed equally to this work.