Cx43 in mitochondria participates in the protection for heptanol preconditioning on myocardial ischemia/reperfusion injury of rabbits / 中国药理学通报

ABSTRACT

Aim To investigate the roles of Cx43 in mitochondria and mitochondrial ATP sensitive potassium channe1(mitoK_(ATP)~+)participating in the protection for heptanol preconditioning on myocardial ischemia/reperfusion injury of rabbits.Methods In anesthetized open-chest rabbits,the left anterior descending artery(LAD)was occluded for 30 min and reperfused for 4 hrs.All rabbits were randomly divided into five groups(n=16 in each group)sham operation group(Group Sham),ischemic reperfusion group(Group IR),ischemic preconditioning group(Group IP),heptanol preconditioning group(Group HT)and 5-HD plus heptanol preconditioning group(Group HT+5-HD),All rabbits in the five groups were killed 4h after reperfusion.Myocardial infarct size was determined at the end of the experiment.The heart rate and the mean arterial pressure(MAP)were recorded and plasma CK-MB and cTnI activity were measured at baseline,the end of ischemia,and after 2 hrs and 4 hrs of reperfusion respectively.Mitochondria was isolated with different centrifugations.Ultrastructural changes of mitochondria were observed under electron microscope.The content of the mitochondria Cx43 was detected with Western blot.Results The plasma CK-MB,cTnI activity and myocardial infarct size were significantly reduced in IP(18.97±2.8)% and HT(19.97±3.8)% groups as compared to IR groups (35.67±5.8)%,(P<0.01).Compared to group IR,the damage of mitochondria in group IP and group HT were milder(P<0.01).No significant difference was found between Group IP and Group HT.Compared to sham group, the mitochondria Cx43 expression was distinctly decreased in group IR and group HT+5-HD(P<0.01)and no significant difference was found between Group IP and Group HT.Conclusions Heptanol preconditioning can protect the heart from I/R injury by improving mitochondrial ultrastructure and by attenuating the decrease of mitochondria Cx43 expression induced by I/R.The mitochondrial Cx43 expression may be concerned with depending on mito K_(ATP)~+.