Comparison of cardio-protective effects induced by different modalities of sevoflurane conditioning in isolated rat hearts

OBJECTIVE: To examine whether the combination of anesthetic preconditioning and anesthetic postconditioning could elicit additional cardio-protection as compared to either anesthetic preconditioning or anesthetic postconditioning alone and its underlying mechanism. METHODS: Isolated rat hearts were randomized into one of four groups: CTRL group (30 min of ischemia followed by 120 min of reperfusion alone); SpreC group (3% sevoflurane preconditioning was administered for 15 min followed by 10 min of washout before ischemia); SpostC group (3% sevoflurane postconditioning was administered during the first 15 min of reperfusion after ischemia); SpreC+SpostC group (the protocols of SpreC and SpostC were combined). Hemodynamics, myocardial infarct size, lactate dehydrogenase and creatine kinase-MB in collected effluent, phosphorylation of PKB/Akt and ERK 1/2 and content of nicotinamide adenine dinucleotide in the left ventricular tissue were compared among the four groups. RESULTS: When compared with unprotected Control hearts, those in the sevoflurane-treated groups (SpreC, SpostC and SpreC+SpostC) showed significantly better functional recovery, reduced myocardial infarct size and decreased lactate dehydrogenase and creatine kinase-MB release. Comparison of the above-mentioned variables among the three sevoflurane-treated groups showed that maximal cardio-protection was obtained in the SpreC+SpostC group. Both SpreC and SpreC+SpostC induced a biphasic response in protein kinase B (PKB/Akt) and extracellular signal-regulated kinase (ERK 1/2) phosphorylation, while SpostC induced only one phase. The effects on phosphorylation of both PKB/Akt and ERK 1/2 induced by SpreC and SpostC were found to be additive during reperfusion. The combination of SpreC and SpostC also had additive effects on inhibiting mitochondrial permeability transition pore (mPTP) opening induced by ischemia-reperfusion. CONCLUSION: These findings suggested that the cardio-protection induced by SpreC and SpostC could be additive via the involvement of PKB/Akt, ERK 1/2 and mPTP.