title: Calcium-dependent increase in the potassium permeability of human red blood cells by pentachlorophenol and 2,4,6-trinitrophenol.
abstract: The effects of four phenol derivatives on the Ca2+ and K+ permeability of human red cells were studied at 0 degree C using 45Ca2+ and 86Rb+. Pentachlorophenol (PCP) and 2,4,6-trinitrophenol (TNP), which are mainly ionized at physiological pH, produced a marked influx of Ca2+ that increased with increasing pH. The elevated intracellular Ca2+ concentration was completely (TNP 5-10 mM, PCP 0.5 mM) or partly (PCP 1.0 mM) responsible for a concomitant increase in potassium permeability. No effects were found in connection with the weakly ionized 4-CI and 4-CI-3,5-di-CH3 derivatives at 1.0-5.0 mM and 0.5-2.0 mM, respectively. The fact that ionized phenols are able to transfer Ca2+ from water to a hydrophobic phase suggests that they may act as weak Ca2+ ionophores in the red cell plasma membrane.
mesh_terms: D002118:Calcium / Q000502:physiology*; D002463:Cell Membrane Permeability / Q000187:drug effects; D002733:Chlorophenols / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D004910:Erythrocyte Membrane / Q000187:drug effects*; D004912:Erythrocytes / Q000187:drug effects*; D007473:Ion Channels / Q000187:drug effects; D007476:Ionophores / Q000494:pharmacology; D009578:Nitrobenzenes / Q000494:pharmacology*; D010416:Pentachlorophenol / Q000494:pharmacology*; D011188:Potassium / Q000378:metabolism*; D014301:Trinitrobenzenes / Q000494:pharmacology*
chemical_list: D002733:Chlorophenols; D007473:Ion Channels; D007476:Ionophores; D009578:Nitrobenzenes; D014301:Trinitrobenzenes; D004533:Egtazic Acid; D010416:Pentachlorophenol; D011188:Potassium; D002118:Calcium