Objective: Haemodynamics

myocardial infarction size

ultrastructure of myocardial tissue following infusion with propofol and midazolam have been compared in rats with acute myocardial infarction. Methods: Seventy-two Wistar rats with acute myocardial infarction were randomly divided into 9 groups

with group I as control(C)

the other rats infused with 30（P1）

45（P2）

60（P3）

75（P4）mg/kg/h of propofol and 45 (M1)

67.5(M2)

90(M3)

112.5(M4) mg/kg/h of midazolam for 30 minutes

respectively. After 30 minutes infusion

the haemodynamic changes and ultrastructure of myocardial tissues were observed，and plasmas concentration of propofol and myocardial infarction size were measured. Results: At the average plasma concentration of propofol at the range of (3.4±0.9～12.9±2.4)μg/ml，it caused a greater decrease in the mean arterial pressure(MAP)

the heart rate (HR)

the left ventricular systolic pressure (LVSP)

the maxium and minimum first derivative of left ventricular(LV±dp/dt max) and cardial oxygen consumpution index (Omcci) than equipotent midazolam（P<0.05）

But the left ventricular end-diastolic pressure (LVEDP) had no significant changes in all rats (P>0.05). Myocardial infarction size in propofol group and midazolam group were23.7%~29.2% and 24.3%~28.9% respectively. There were no significant changes in myocardial infarction size and ultrastructure of myocardial tissue (P>0.05). Conclusion: Midazolam may be less depressant to cardiovascular system than propofol in the rat with acute myocardial infarction. There are no significant changes in myocardial infarction size and ultrastructure of myocardial tissue in all groups.