Effect of volatile anesthetics on ryanodine binding in skeletal muscle

We determined the effect of isoflurane, halothane, and xenon on [H-3]-ryano dine binding in skeletal muscle sarcoplasmic reticulum. [H-3]-ryanodine bin ding 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 m M KCl) isoflurane stimulated ryanodine binding with a bell-shaped dose resp onse curve (peak stimulation averaged +79% and occurred with 6 mM isofluran e). Halothane slightly stimulated ryanodine binding at 2-4 mM concentration , and inhibited it at 10 mM concentration. At high ionic strength(I M KCl) both isoflurane and halothane inhibited ryanodine binding. Xenon was tested at 70% gas concentration: it inhibited (by 10%) ryanodine binding at low i onic strength and stimulated (by 31%) ryanodine binding at high ionic stren gth. The different effect of xenon vs halogenated anesthetics might have cl inical importance in patients susceptible to malignant hyperthermia.