title: Dual exposure to sevoflurane improves anesthetic preconditioning in intact hearts.
abstract: BACKGROUND
  Anesthetic preconditioning (APC) with sevoflurane reduces myocardial ischemia-reperfusion injury. The authors tested whether two brief exposures to sevoflurane would lead to a better preconditioning state than would a single longer exposure and whether dual exposure to a lower (L) concentration of sevoflurane would achieve an outcome similar to that associated with a single exposure to a higher (H) concentration.
  
  
  METHODS
  Langendorff-prepared guinea pig hearts were exposed to 0.4 mM sevoflurane once for 15 min (H1-15; n = 8) or 0.4 mM (H2-5; n = 8) or 0.2 mM sevoflurane (L2-5; n = 8) twice for 5 min, with a 5-min washout period interspersed. Sevoflurane was then washed out for 20 min before 30 min of global no-flow ischemia and 120 min of reperfusion. Control hearts (n = 8) were not subjected to APC. Left ventricular pressure was measured isovolumetrically. Ventricular infarct size was determined by tetrazolium staining and cumulative planimetry. Values are expressed as mean +/- SD.
  
  
  RESULTS
  The authors found a better functional return and a lesser percentage of infarction on reperfusion in H2-5 (28 +/- 9%) than in H1-15 (36 +/- 8%; P < 0.05), L2-5 (43 +/- 6%; P < 0.05), or control hearts (52 +/- 7%; P < 0.05).
  
  
  CONCLUSIONS
  These results suggest that APC depends not only on the concentration but also on the protocol used for preconditioning. Similarly to ischemic preconditioning, repeated application of the volatile anesthetic seems to be more important than the duration of exposure in initiating the signaling sequence that elicits APC at clinically relevant concentrations. Therefore, repeated cycles of anesthetic exposure followed by volatile anesthetic-free periods may be beneficial for APC in the clinical setting.
authors.affiliation: Anesthesiology Research Laboratories, Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
authors.forename: Matthias L
authors.initials: ML
authors.lastname: Riess
authors.forename: Leo G
authors.initials: LG
authors.lastname: Kevin
authors.forename: Amadou K S
authors.initials: AK
authors.lastname: Camara
authors.forename: James S
authors.initials: JS
authors.lastname: Heisner
authors.forename: David F
authors.initials: DF
authors.lastname: Stowe
mesh_terms: D018685:Anesthetics, Inhalation / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D003326:Coronary Circulation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D019157:Ischemic Preconditioning, Myocardial; D008738:Methyl Ethers / Q000008:administration & dosage / Q000494:pharmacology*; D009203:Myocardial Infarction / Q000473:pathology; D015428:Myocardial Reperfusion Injury / Q000473:pathology; D009206:Myocardium / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects; D000077149:Sevoflurane; D016277:Ventricular Function, Left / Q000187:drug effects
chemical_list: D018685:Anesthetics, Inhalation; D008738:Methyl Ethers; D000077149:Sevoflurane