The Effect Of Urocrotin ? Postconditioning On Mitochondrial Permeability Transition Pore And Apoptosis Proteins Bax?Bcl-2in Rat Heart During Hypoxia/reoxygenation Injury

Objective:To observe the effect of urocrotin I postconditioning on mitochondrial permeability transition pore and apoptosis proteins Bax?Bcl-2 in rat heart during hypoxia/reoxygenation injury,to explore the mitochondrial mechanism in cardioprotection.Methods:Isolated rat heart by using MPA isolated heart perfusion device.Myocytes after being continuously cultivated 24 h were randomly divided into four groups:Nor group,HR group,Ucn I postconditioning group and mitochondrial ATP-sensitive potassium channel blocker 5-HD+Ucn I group.Nor group:cultivated in a 37? incubator continuously for 150min;HR group:experienced anoxia for 40 min,then reoxygenation for 110min;Ucn I group:reoxygenation for 10 min after experiencing anoxia for 40 min,then cultivated in a nutrient medium containing Ucn I for 30 min,and then reoxygenation for 70 min.5-HD+Ucn I group:cultivated in a nutrient medium containing 5-HD for 10 min before reoxygenation,the rest managements were the same as Ucn I group.Observing the following indexes at the end of reoxygenation:(1)the change of m PTP?MMP?ROS were scaned by using inverted phase contrast microscope;(2)apoptosis protein Bax?Bcl-2 were detected by using Westernblot method;(3)cell viability were detected by using CCK-8 kit.Results:1?Fluorescence intensity change of m PTP and ROS:Nor group was lower than other three groups(P<0.01);HR group were higher than groups Ucn I and 5-HD+Ucn I(P<0.01);while 5-HD+Ucn I group was higher than Ucn I group.2?Fluorescence intensity change of MMP:Nor group was higher than other three groups(P<0.01);Ucn I group was lower than Nor group,but higher than groups HR and 5-HD+Ucn I(P<0.05);but there was no significant difference between groups HR and 5-HD+Ucn I(P>0.05).3?The expression of Bax?Bcl-2 proteins:Compared with other groups,Nor group had the lowest expression of Bax,but thehighest expression of Bcl-2(P<0.01);the expression of Bax in Ucn I group was lower than groups HR and 5-HD+Ucn I(P<0.05),Bcl-2 was higher than groups HR and 5-HD+Ucn I(P<0.05);the expression of Bax and Bcl-2 had no significant difference between groups HR and 5-HD+Ucn I(P>0.05).4?Change of cell viability: Nor group was higher than other groups(P<0.01);Ucn I group was lower than Nor group,but higher than groups HR and 5-HD+Ucn I(P<0.05),there was no significant difference between groups HR and 5-HD+Ucn I(P>0.05).Conclusion:Ucn I postconditioning can sustain the viability of myocytes suffering anoxia/reoxygenation injury to exert its cardioprotective effects.The possible mechanism maybe relate to its characteristics that Ucn I can activate mitochondrial ATPsensitive potassium channel,decrease the production of ROS to avoid the destruction of cytomembrane,thus inhibiting the open of m PTP,maintaining MMP,decreasing the releasing of pro-apoptosis proteins such as Bax and so on.