Inhaled sevoflurane produces better delayed myocardial protection at 48 versus 24 hours after exposure

Ischemia preconditioning produces a delayed window of cardioprotection against subsequent ischemia and reperfusion injury. Contradictory results have been reported regarding the ability of inhaled anesthetics to produce similar effects. Our investigation was designed to test whether inhaled sevoflurane is capable of producing a delayed window of anesthetic preconditioning and to compare the differences at 24 and 48 h after exposure. Male Fischer-344 rats, 2-4 mo old, were exposed to sevoflurane (2.5% for 60 min). Twenty-four or 48 h after exposure, the hearts were isolated and perfused for 30 min (equilibration) followed by 25 min of ischemia and then 60 min of reperfusion. Control hearts received no treatment before ischemia. Left ventricular (LV) function, creatine kinase (CK), and infarct size (IS) were measured. Nuclear magnetic resonance was used to measure Na+(i), Ca2+]i, and pH(i). There was improved LV function and significant reduction in IS and CK and in both the 24- and 48-h delayed groups compared with the controls. There was also a significant recovery of LV function and reduction in IS and CK in the 48-h group when compared with the 24-h group. There was significant adenosine triphosphate preservation in both the 24- and 48-h groups, as well as a significant reduction in acidosis, Ca2+]I, and Na+(i) in response to ischemia in both the groups versus the control. Sevoflurane is capable of producing a delayed window of preconditioning, and it takes more than 24 h to produce maximal protective effects.