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Isoflurane preconditioning confers cardioprotection by activation of ALDH2.

Lang XE, Wang X, Zhang KR, Lv JY, Jin JH, Li QS - PLoS ONE (2013)

Bottom Line: Pretreatment with isoflurane prior to ischemia reduced LDH and CK-MB levels and infarct size, while it increased phosphorylation of ALDH2, which could be blocked by the ALDH2 inhibitor, cyanamide.Hypoxia/reoxygenation (H/R) increased cardiomyocyte apoptosis and injury which were attenuated by isoflurane and forced the activation of ALDH2.In contrast, the effect of isoflurane-induced protection was almost abolished by knockdown of ALDH2.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, The First Clinical Medical College of Shanxi Medical University, Taiyuan, Shanxi, China.

ABSTRACT
The volatile anesthetic, isoflurane, protects the heart from ischemia/reperfusion (I/R) injury. Aldehyde dehydrogenase 2 (ALDH2) is thought to be an endogenous mechanism against ischemia-reperfusion injury possibly through detoxification of toxic aldehydes. We investigated whether cardioprotection by isoflurane depends on activation of ALDH2.Anesthetized rats underwent 40 min of coronary artery occlusion followed by 120 min of reperfusion and were randomly assigned to the following groups: untreated controls, isoflurane preconditioning with and without an ALDH2 inhibitor, the direct activator of ALDH2 or a protein kinase C (PKCε) inhibitor. Pretreatment with isoflurane prior to ischemia reduced LDH and CK-MB levels and infarct size, while it increased phosphorylation of ALDH2, which could be blocked by the ALDH2 inhibitor, cyanamide. Isolated neonatal cardiomyocytes were treated with hypoxia followed by reoxygenation. Hypoxia/reoxygenation (H/R) increased cardiomyocyte apoptosis and injury which were attenuated by isoflurane and forced the activation of ALDH2. In contrast, the effect of isoflurane-induced protection was almost abolished by knockdown of ALDH2. Activation of ALDH2 and cardioprotection by isoflurane were substantially blocked by the PKCε inhibitor. Activation of ALDH2 by mitochondrial PKCε plays an important role in the cardioprotection of isoflurane in myocardium I/R injury.

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PKCε translocation is involved in isoflurane preconditioning.A PKCε translocation was associated with isoflurane-induced phosphorylation of ALDH2. (a) Representative of western blot analysis of phos-ALDH2, total ALDH2, β-actin, mitochondria PKCε (mito-PKCε) and total PKCε (from top lanes to bottom lanes). β-actin was used to demonstrate equal protein loading. (b) Quantification of the phos-ALDH2, normalized to the total ALDH2, and PKCε translocation to the mitochondria from 3 different experiments. B, C. Isoflurane-induced inhibition of LDH and CK-MB release by I/R was restored by PKCε v1–2. Serum LDH and CK-MB concentrations were analyzed. D. PKCε v1–2 inhibits the decrease in heart infarct size caused by isoflurane following I/R. Representative cross-sectional slices derived from a single heart. The infarct size normalized to the area at risk. Values are means ± S.E.M., n = 8 in each group. *P<0.05, **P<0.01 vs. the saline control group and #P<0.05, ##P<0.01 with PKCε v1–2 vs. the corresponding group without PKCε v1–2.
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pone-0052469-g005: PKCε translocation is involved in isoflurane preconditioning.A PKCε translocation was associated with isoflurane-induced phosphorylation of ALDH2. (a) Representative of western blot analysis of phos-ALDH2, total ALDH2, β-actin, mitochondria PKCε (mito-PKCε) and total PKCε (from top lanes to bottom lanes). β-actin was used to demonstrate equal protein loading. (b) Quantification of the phos-ALDH2, normalized to the total ALDH2, and PKCε translocation to the mitochondria from 3 different experiments. B, C. Isoflurane-induced inhibition of LDH and CK-MB release by I/R was restored by PKCε v1–2. Serum LDH and CK-MB concentrations were analyzed. D. PKCε v1–2 inhibits the decrease in heart infarct size caused by isoflurane following I/R. Representative cross-sectional slices derived from a single heart. The infarct size normalized to the area at risk. Values are means ± S.E.M., n = 8 in each group. *P<0.05, **P<0.01 vs. the saline control group and #P<0.05, ##P<0.01 with PKCε v1–2 vs. the corresponding group without PKCε v1–2.

Mentions: PKCε translocation to mitochondria and then phosphorylation of ALDH2 is required to protect the heart from I/R injury. Here we demonstrate that pretreatment with isoflurane resulted in elevated mitochondrial levels of PKCε accompanied by phosphorylation of ALDH2. Isoflurane-induced phosphorylation of ALDH2 was inhibited by the PKCε inhibitor, PKCε V1–2. Because mitochondrial translocation of PKCε occurs rapidly, with a corresponding decline in cytosolic PKCε levels, and because the total cellular PKCε levels do not change (Figure 5A), our data suggest that isoflurane enables dynamic mitochondrial translocation of PKCε in response to I/R. Consistent with PKCε translocation to mitochondria, PKCε V1–2 had a detrimental effect on isoflurane-induced attenuation of LDH and CK-MB leakage (Figure 5B, 5C), and the decrease in myocardial infarct size (Figure 5D).


Isoflurane preconditioning confers cardioprotection by activation of ALDH2.

Lang XE, Wang X, Zhang KR, Lv JY, Jin JH, Li QS - PLoS ONE (2013)

PKCε translocation is involved in isoflurane preconditioning.A PKCε translocation was associated with isoflurane-induced phosphorylation of ALDH2. (a) Representative of western blot analysis of phos-ALDH2, total ALDH2, β-actin, mitochondria PKCε (mito-PKCε) and total PKCε (from top lanes to bottom lanes). β-actin was used to demonstrate equal protein loading. (b) Quantification of the phos-ALDH2, normalized to the total ALDH2, and PKCε translocation to the mitochondria from 3 different experiments. B, C. Isoflurane-induced inhibition of LDH and CK-MB release by I/R was restored by PKCε v1–2. Serum LDH and CK-MB concentrations were analyzed. D. PKCε v1–2 inhibits the decrease in heart infarct size caused by isoflurane following I/R. Representative cross-sectional slices derived from a single heart. The infarct size normalized to the area at risk. Values are means ± S.E.M., n = 8 in each group. *P<0.05, **P<0.01 vs. the saline control group and #P<0.05, ##P<0.01 with PKCε v1–2 vs. the corresponding group without PKCε v1–2.
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pone-0052469-g005: PKCε translocation is involved in isoflurane preconditioning.A PKCε translocation was associated with isoflurane-induced phosphorylation of ALDH2. (a) Representative of western blot analysis of phos-ALDH2, total ALDH2, β-actin, mitochondria PKCε (mito-PKCε) and total PKCε (from top lanes to bottom lanes). β-actin was used to demonstrate equal protein loading. (b) Quantification of the phos-ALDH2, normalized to the total ALDH2, and PKCε translocation to the mitochondria from 3 different experiments. B, C. Isoflurane-induced inhibition of LDH and CK-MB release by I/R was restored by PKCε v1–2. Serum LDH and CK-MB concentrations were analyzed. D. PKCε v1–2 inhibits the decrease in heart infarct size caused by isoflurane following I/R. Representative cross-sectional slices derived from a single heart. The infarct size normalized to the area at risk. Values are means ± S.E.M., n = 8 in each group. *P<0.05, **P<0.01 vs. the saline control group and #P<0.05, ##P<0.01 with PKCε v1–2 vs. the corresponding group without PKCε v1–2.
Mentions: PKCε translocation to mitochondria and then phosphorylation of ALDH2 is required to protect the heart from I/R injury. Here we demonstrate that pretreatment with isoflurane resulted in elevated mitochondrial levels of PKCε accompanied by phosphorylation of ALDH2. Isoflurane-induced phosphorylation of ALDH2 was inhibited by the PKCε inhibitor, PKCε V1–2. Because mitochondrial translocation of PKCε occurs rapidly, with a corresponding decline in cytosolic PKCε levels, and because the total cellular PKCε levels do not change (Figure 5A), our data suggest that isoflurane enables dynamic mitochondrial translocation of PKCε in response to I/R. Consistent with PKCε translocation to mitochondria, PKCε V1–2 had a detrimental effect on isoflurane-induced attenuation of LDH and CK-MB leakage (Figure 5B, 5C), and the decrease in myocardial infarct size (Figure 5D).

Bottom Line: Pretreatment with isoflurane prior to ischemia reduced LDH and CK-MB levels and infarct size, while it increased phosphorylation of ALDH2, which could be blocked by the ALDH2 inhibitor, cyanamide.Hypoxia/reoxygenation (H/R) increased cardiomyocyte apoptosis and injury which were attenuated by isoflurane and forced the activation of ALDH2.In contrast, the effect of isoflurane-induced protection was almost abolished by knockdown of ALDH2.

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, The First Clinical Medical College of Shanxi Medical University, Taiyuan, Shanxi, China.

ABSTRACT
The volatile anesthetic, isoflurane, protects the heart from ischemia/reperfusion (I/R) injury. Aldehyde dehydrogenase 2 (ALDH2) is thought to be an endogenous mechanism against ischemia-reperfusion injury possibly through detoxification of toxic aldehydes. We investigated whether cardioprotection by isoflurane depends on activation of ALDH2.Anesthetized rats underwent 40 min of coronary artery occlusion followed by 120 min of reperfusion and were randomly assigned to the following groups: untreated controls, isoflurane preconditioning with and without an ALDH2 inhibitor, the direct activator of ALDH2 or a protein kinase C (PKCε) inhibitor. Pretreatment with isoflurane prior to ischemia reduced LDH and CK-MB levels and infarct size, while it increased phosphorylation of ALDH2, which could be blocked by the ALDH2 inhibitor, cyanamide. Isolated neonatal cardiomyocytes were treated with hypoxia followed by reoxygenation. Hypoxia/reoxygenation (H/R) increased cardiomyocyte apoptosis and injury which were attenuated by isoflurane and forced the activation of ALDH2. In contrast, the effect of isoflurane-induced protection was almost abolished by knockdown of ALDH2. Activation of ALDH2 and cardioprotection by isoflurane were substantially blocked by the PKCε inhibitor. Activation of ALDH2 by mitochondrial PKCε plays an important role in the cardioprotection of isoflurane in myocardium I/R injury.

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Related in: MedlinePlus