Chronic exposure to inhaled anesthetics increases cholesterol content in Acholeplasma laidlawii.
Acholeplasma laidlawii cells were grown in cholesterol-enriched medium and exposed continuously to either air (control), 4.0 vol.% halothane in air at 1 atm pressure (4% atm halothane), or 80% cyclopropane in oxygen for 24 h at 37 degrees C. Cells grown in the presence of 4% atm halothane or 80% cyclopropane had approximately twice as much membrane cholesterol content/mg protein as the control cells. Cells grown in an anesthetic environment also tended to have a higher membrane cholesterol/phospholipid molar ratio compared to control cells. Membranes isolated from halothane-exposed cells grown in a cholesterol-enriched medium were more ordered at 37 degrees C (measurements were made with no anesthetic present) than membranes from control cells grown in an identically enriched medium. This difference in membrane physical state between control and anesthetic-exposed cells decreased as the temperature decreased, and disappeared at approx. 23 degrees C. Continuous exposure of A. laidlawii to 4% atm halothane or 80% cyclopropane for 24 h did not markedly affect membrane fatty acid composition, either in cells grown on an unsupplemented medium or in cells grown in a medium enriched in myristic, palmitic or stearic acids. These results further support the hypothesis that an increased membrane cholesterol content may play a role in the tolerance or dependence that develops after chronic exposure to anesthetic agents.
D000128:Acholeplasma laidlawii / Q000187:drug effects / Q000378:metabolism*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism*; D003521:Cyclopropanes / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D005227:Fatty Acids / Q000032:analysis; D006221:Halothane / Q000494:pharmacology*; D008565:Membrane Proteins / Q000378:metabolism*; D013696:Temperature
D003521:Cyclopropanes; D005227:Fatty Acids; D008565:Membrane Proteins; D002784:Cholesterol; D006221:Halothane