Proliferation of Smooth Endoplasmic Reticulum and Induction of Microsomal Drug-metabolizing Enzymes after Ether or Halothane

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Abstract
Hepatic drug-metabolizing enzymes and hepatic ultrastructure were studied in rats after 2 h of anesthesia with 1 MAC [minimum alveolar concentration] halothane or diethyl ether. Twelve hours after cessation of either anesthetic smooth endoplasmic reticulum was increased in centrilobular but not in periportal hepatocytes. This change persisted at 24 and 36 h sampling times. Microsomal cytochrome P450 and cytochrome b5 decreased after halothane anesthesia (by 7-20% of control). Diethyl ether caused increased cytochrome P450 and cytochrome b5 (27 and 18%, respectively) at the 36-h sampling time. NADPH cytochrome c reductase did not change significantly after either agent. Both agents may promote conversion of rough endoplasmic reticulum to smooth endoplasmic reticulum or, alternatively, that the anesthetics decrease degradation of smooth endoplasmic membranes. Since only ether caused an increase in the microsomal content of enzymes of the drug-metabolizing enzyme system, it is concluded that these 2 anesthetics act on hepatic cells by dissimilar mechanisms.