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Title: Kinetic and pharmacological properties of the calcium-activated chloride-current in macrovascular endothelial cells
Authors: Nilius, Bernd ×
Prenen, Jean
Voets, Thomas
Van Den Bremt, Karen
Eggermont, Jan
Droogmans, Guillaume #
Issue Date: Jul-1997
Series Title: Cell calcium. vol:22 issue:1 pages:53-63
Abstract: We have studied the kinetic and pharmacological properties of the Ca(2+)-activated Cl- current (ICl,Ca) in cultured cell pulmonary artery endothelial (CPAE) cells by means of combined patch clamp and Fura-2 micro fluorescence measurements. The current was activated by loading the cells via the patch pipettes with Ca(2+)-buffered solutions. Currents activated slowly at positive potentials, and decayed rapidly at negative potentials. The time constant of activation decreased at more positive membrane potentials and more elevated intracellular Ca2+ concentrations ([Ca2+]i). The time constant of deactivation was Ca(2+)-independent and decreased at more negative potentials. Steady-state currents showed strong outward rectification, but the instantaneous current-voltage relationship was almost ohmic. The calmodulin antagonists trifluoperazine (TFP) and calmidazolium inhibit ICl,Ca. Half maximal block for TFP occurred at 5.7 +/- 2.1 microM (n = 16). GTP gamma S did not activate ICl,Ca, but activated a Cl- current similar to the volume-activated Cl- current (ICl,vol). [Ca2+]i for half maximal activation of ICl,Ca was voltage-dependent, and suggests that the apparent binding constant for Ca2+ decreases with depolarization. Its value at 0 mV is 430 nM, and the binding site is 12% within the electrical field from the cytoplasmic side. The Hill-coefficient, nH, of the binding was larger than 1 and increased with depolarization. The maximal Cl- conductance at saturating [Ca2+]i did not depend on the membrane potential. RT-PCR experiments did not provide any evidence that the endothelial Ca(2+)-activated Cl- channel might be identical with a recently cloned Ca(2+)-sensitive Cl- channel (CaCC).
ISSN: 0143-4160
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Physiology Section (-)
Laboratory of Ion Channel Research
Department of Cellular and Molecular Medicine - miscellaneous
Laboratory of Cellular Transport Systems
× corresponding author
# (joint) last author

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