Effect of antihistamines and chlorpromazine on the calcium-induced hyperpolarization of the Amphiuma red cell membrane |
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Authors: | George G rdos, Ulrik V. Lassen,Leon Pape |
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Affiliation: | 1. Department of Cell Metabolism, National Institute of Haematology and Blood Transfusion, Budapest Hungary;2. Zoophysiological Laboratory B, University of Copenhagen, Copenhagen Denmark |
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Abstract: | 1. 1. It has previously been demonstrated that an increase in extracellular Ca2+ concentration induces a transient increase in K+ permeability and associated hyperpolarization of the red cell membrane of the giant salamander, Amphiuma means. This phenomenon is analogous to the Ca2+-induced KCl loss observed in ATP-depleted human red cells and red cell ghosts. 2. 2. Histamine, which enhances the Ca2+-induced K+ loss from depleted human red cells, is without effect on this Ca2+-induced hyperpolarization of Amphiuma red cells. 3. 3. Promethazine (10 μM) and mepyramine (1 mM), which inhibit the Ca2+-induced K+ loss in depleted human red cells, also block the Ca2+-related hyperpolarization of Amphiuma erythrocytes. 4. 4. Chlorpromazine (25 μM), despite being a weak antihistamine, is equally effective in blocking the Ca2+-induced hyperpolarization of Amphiuma red cells. 5. 5. Ionophore A23187 causes a large and sustained Ca2+/K+-dependent hyperpolarization even in the presence of normal (1.8 mM) concentrations of Ca2+. This hyperpolarization is relatively insensitive to chlorpromazine and promethazine. 6. 6. The inhibition of the Ca2+-induced hyperpolarization of the Amphiuma red cell membrane by chlorpromazine and promethazine may be related to their properties as local anaesthetics. Abbreviations: MOPS, morpholinopropane sulphonate |
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Keywords: | MOPS morpholinopropane sulphonate |
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