Objective    To investigate the relationship of antishock effect of arginine vasopressin (AVP) on hemorrhagic shock and its relationship with Rho kinase.     Methods    Hemorrhagic shock (40 mmHg for 2 h) Wistar rats were treated respectively by AVP (0.4 U/kg)

Rho kinase specific inhibitor

Y-27632 (30 μg/kg)

or these 2 reagents. The pressor effect of norepinephrine (NE) on these rats and the contractility of their isolated superior mesenteric artery (SMA) were observed. Isolated SMAs from hemorrhagic shock rats were adopted to observe the effects of AVP on vascular reactivity and calcium sensitivity and its relationship to Rho kinase with an isolated organ perfusion system.     Results    AVP at the concentration of 0.4 U/kg significantly improved the pressor effect of NE and the contractile response of SMA. While

Y-27632 (30 μg/kg) abolished these beneficial effects of AVP. The vascular reactivity and calcium sensitivity of SMA were significantly decreased following hemorrhagic shock. AVP at the concentration of 0.5 and 5 nmol/L significantly increased the decreased vascular reactivity and calcium sensitivity. These effects of AVP were abolished by Y-27632 (10 μmol/L).     Conclusion    Rho kinase may take part in the action of AVP on hemorrhagic shock via improving shock induced vascular hyporeactivity and calcium desensitization.