Objective To study the proper volume of different fluids to resuscitate hemorrhagic shock in rats.   Methods SD rats were hemorrhaged to 35% or 45% total blood volume. Then lactated ringer’s (LR) of 1×

2×

3× shed blood volume

20 or 30 ml/kg hydroxyethyl starch (HES)

7.5%NaCl/

6%Dextran40 (HSD) at dose of 4

6

8 ml/kg

LR+HES of 1×

2×

3× shed blood volume were transfused to resuscitate the rats

respectively. Mean arterial blood pressure (MAP)

left intraventricular systolic pressure (LVSP)

the maximal change rate of left intraventricular pressure (±dp/dt

max

) were observed before and after hemorrhagic shock

1 and 2 hours after transfusion. Blood gas was detected 1 h after transfusion and at the end of transfusion and 12-hour survival rate of the animals was also observed.   Results For the rats with 35% total blood loss

the effects of LR and HSD on hemodynamic parameters were not significantly different. HES at dose of 30 ml/kg and HES+LR of 2× shed blood volume improved hemodynamic parameters and the survival rate as compared with HES at 20 ml/kg and other LR+HES groups. For the rats with 45% total blood loss

LR of 3× shed blood volume and HSD at 6 ml/kg improved hemodynamics better than LR of 1×

2× shed blood volume and HSD at 4 and 8 ml/kg. Similarly

HES at 30 ml/kg and LR+HES of 2× shed blood volume improved the hemodynamic parameters and survival rate better than HES at 20 ml/kg and HES+LR of 1×

2×shed blood volume. For blood gas

all fluids had no obvious effect

except that HSD significantly decreased the blood pH value.   Conclusion  Besides LR of 3× shed blood volume is effective in resuscitating the rats of 45% total blood loss

the transfusion of HES at 30 ml/kg

HSD at 6 ml/kg or LR+HES of 2× shed blood volume achieves better resuscitation effect in the rats of 35% or 45% total blood loss.