Objective:To observe the effects of prolonged transient acidosis on cardiac hemodynamics in aged rat heart after reperfusion injury.Methods:60 isolated SD rats hearts(≥18 months)perfused by Langendorff were randomly divided into 6 groups(n=10):(1)normal contro1(C)group;(2)reperfusion injury(I/R)group;(3)ischemic postconditioning(IPO)group;(4)acidosis(H+)group;(5)postconditioning+alkalotic(IPO+OH-)group;(6)alkalotic(OH-)group.The direct effects of prolonged transient acidosis on myocardiac contractility were observed by a langendorff apparatus through the hemodynamics parameters including heart rate(HR)

left ventricular systolic pressure(LVSP)

left ventricular end-diastolic pressure(LVEDP)

and ±dp/dtmax.Results:The LVEDP were increased and HR

LVSP

±dp/dtmax were decreased in I/R group

IPO group

H+ group

IPO+OH-group and OH-group compared with those in C group(P <0.05).The LVEDP were decreased and HR

LVSP

±dp/dtmax were increased in IPO group and H+ group compared with those in I/R group(P<0.05).Conclusion:By comparsion with hemodynamics parameters

prolonged transient acidosis can protect isolated rat heart as well as postconditioning

and it has the same role on aged rat.