Volatile anesthetics decrease calcium content of isolated myocytes.
The calcium transient of myocytes was measured using a fluorescent dye, Fura-2. Caffeine, halothane, enflurane, and isoflurane increased the resting calcium level and decreased the calcium transient. The amount of caffeine-induced calcium release was suppressed if myocytes were pretreated with halothane. The amount of halothane-induced calcium release was suppressed if myocytes were pretreated with caffeine. Both halothane and caffeine were found to have similar effects on the sarcoplasmic reticulum (SR). The effect of 4 mM halothane (equivalent to 13.6% v/v) was approximately equivalent to that of 10 mM caffeine. Caffeine, halothane, enflurane, and isoflurane all decreased the total calcium content of myocytes by 10-70%. These data suggest that volatile anesthetics decrease the calcium content of the cardiac SR by increasing the calcium permeability of the SR, and that the mechanism of action of volatile anesthetics may be similar to certain actions of caffeine.