Gender differences in cardioprotection against ischemia/reperfusion injury in adult rat hearts: focus on Akt and protein kinase C signaling

S Bae, L Zhang - Journal of Pharmacology and Experimental …, 2005 - ASPET
Journal of Pharmacology and Experimental Therapeutics, 2005ASPET
Previous studies have reported the sex differences in heart susceptibility to
ischemia/reperfusion (I/R) injury, but the mechanisms are not understood. The present study
tested the hypothesis that Akt and protein kinase C (PKC) ϵ play an important role in the
sexual dimorphism of heart susceptibility to I/R injury. Isolated hearts from 2-month-old male
and female rats were subjected to I/R in the Langendorff preparation. The postischemic
recovery of left ventricular function was significantly better, and infarct size was significantly …
Previous studies have reported the sex differences in heart susceptibility to ischemia/reperfusion (I/R) injury, but the mechanisms are not understood. The present study tested the hypothesis that Akt and protein kinase C (PKC)ϵ play an important role in the sexual dimorphism of heart susceptibility to I/R injury. Isolated hearts from 2-month-old male and female rats were subjected to I/R in the Langendorff preparation. The postischemic recovery of left ventricular function was significantly better, and infarct size was significantly smaller in female (37.1 ± 1.9%) than in male (48.3 ± 2.3%) hearts after 25-min ischemia followed by 2-h reperfusion. Inhibition of phosphatidylinositol 3-kinase/Akt pathway by wortmannin or PKC by chelerythrine chloride before ischemia significantly reduced postischemic recovery and increased infarct size in female but not male hearts. There were no differences in myocardial protein levels of heat shock protein 70, Akt, and PKCϵ, respectively, between male and female rats. However, the ratio of phosphorylated (p)-Akt/Akt (0.58 ± 0.05 versus 0.22 ± 0.04; P < 0.05) and p-PKCϵ/PKCϵ (0.35 ± 0.03 versus 0.22 ± 0.02; P < 0.05) was significantly higher in female than in male hearts. In addition, there were significant increases in p-Akt and p-PKCϵ levels during reperfusion in female but not in male hearts. The results suggest that increased p-Akt and p-PKCϵ levels in female hearts contribute to the gender-related differences in heart susceptibility to I/R and play an important role in cardioprotection against I/R injury in females.
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