Objective          To determine the protective effects of 4-phenylbutyrate (PBA) on traumatic hemorrhagic shock and on vascular reactivity in rats.         Methods        One hundred and ninety-two SD rats (male and female in half

12 to 14 weeks old

weighing 180 to 220 g) were randomly divided into 6 groups

including sham-operation group

shock control group

lactated Ringer’s solution (LR) group

and 5

20 and 50 mg/kg PBA intervention groups (PBA at corresponding doses was added in LR solution). After the establishment of traumatic hemorrhagic shock rats

the effects of PBA on the animal survival

hemodynamics

blood gases and vascular reactivity were observed and compared.         Results         PBA improved survival outcomes of traumatic hemorrhagic shock rats

with the 24-h survival rate increased from 0 in the shock group and 19% in the LR group to 75% in PBA 20 mg/kg intervention group

and the survival time of shock rats increased to 19.9 h in PBA 20 mg/kg group from 3.2 h in shock group and 10.8 h in LR group. Administration of PBA 20 mg/kg made the parameters of hemodynamics and blood gases better than those alone with LR resuscitation (P0.05 to 0.01). And PBA also markedly increased the vascular constriction and relaxation after shock

by the constriction and vasodilator reactivity increasing to 80.2% and 93.1% in PBA 20 mg/kg group from 63.3% and 73.3% in LR group

respectively (P0.01).         Conclusion         PBA improves the vascular function

stabilize hemodynamics

and finally exerts the protective effects on traumatic hemorrhagic shock rats.