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| Effect of volatile
anesthetics on ryanodine binding in skeletal muscle Riccardo Zucchi, Simonetta Ronca-Testoni, Francesco Giunta & Giovanni Ronca We determined the effect of isoflurane, halothane, and xenon on [3H]-ryanodine binding in skeletal muscle sarcoplasmic reticulum. [3H]-ryanodine binding depended on the ionic strength of the binding buffer, and increased by 64-fold in the presence of 1 M vs 200 mM KCl. At low ionic strength (200 mM KCl) isoflurane stimulated ryanodine binding with a bell-shaped dose response curve (peak stimulation averaged +79% and occurred with 6 mM isoflurane). Halothane slightly stimulated ryanodine binding at 2-4 mM concentration, and inhibited it at 10 mM concentration. At high ionic strength (1 M KCl) both isoflurane and halothane inhibited ryanodine binding. Xenon was tested at 70% gas concentration: it inhibited (by 10%) ryanodine binding at low ionic strength and stimulated (by 31%) ryanodine binding at high ionic strength. The different effect of xenon vs halogenated anesthetics might have clinical importance in patients susceptible to malignant hyperthermia. Keywords: Ryanodine receptor, sarcoplasmic reticulum, halothane, isoflurane, xenon Applied Cardiopulmonary Pathophysiology 7: 223-226, 1998 R. Zucchi, M.D. |
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