Fig. 4. Direct comparison of halothane, isoflurane, and sevoflurane in protecting against iron-induced lactate dehydrogenase (LDH) release. (A ) Sister cultures were simultaneously treated with one of the anesthetics at a concentration of 0.4 mm during exposure to iron (300 μm, 30 min). Under these conditions, sevoflurane was less protective than either halothane or isoflurane. (B ) The concentrations of volatile anesthetic in the culture medium was adjusted so as to attain equal concentrations of volatile anesthetics in the cell membranes. All anesthetics conferred equivalent protection (P = 0.792). Values are mean ± SD (n = 16) from at least two different culture preparations. ^aP  less than 0.05 versus  controls (LDH release from untreated iron-exposed cultures); ^bP  less than 0.01 versus  halothane-treated iron-exposed cultures; ^cP  less than 0.01 versus  isoflurane-treated iron-exposed cultures. In (A ), 100%= 2.54 ± 0.10 nmol lactate oxidized to pyruvate per minute at room temperature in untreated iron-exposed control cultures. In (B ), 100%= 1.62 ± 0.31 nmol lactate oxidized to pyruvate per minute at room temperature in untreated iron-exposed control cultures.