Objective   To investigate the dynamical changes of asymmetric dimethylarginine (ADMA) and nitric oxide (NO) in the cerebral spinal fluid (CSF) after subarachnoid hemorrhage (SAH)

and access the relationship between the concentrations of ADMA and cerebral vasospasm (CVS).    Methods   An experimental cerebral vasospasm model was established by twice injections of fresh autologous arterial blood into the cisterna magna of 32 white rabbits. Another 8 rabbits receiving sham operation served as sham control. The velocity of basilar artery (BA) was measured by transcranial Doppler(TCD) before the injection and on the 1st

4th

7th day after twice injections. At the same time

the CSF concentrations of ADMA and NO were measured by ELISA and nitrate reductase method respectively.    Results   The concentrations of ADMA in CSF was increased significantly after the injection than that before injection(P0.01)

and was decreased gradually after reaching the highest level on the 4th day. However

the trend of NO were quite opposite(P0.01). The degrees of CVS became serious after SAH and then was relieved gradually after reaching the peak flow velocity of basilar artery on the 4th day. The change of the ADMA in the CSF was synchronal with the velocity of basilar artery. On the 4th day after twice injections

the concentrations of ADMA were correlated negatively with NO level(r=-1.829

P0.01)

but positively with the velocity of basilar artery(r=0.863

P0.01).     Conclusion   The degree of cerebral vasospasm after subarachnoid hemorrhage is positively related to the concentration of ADMA in cerebral spinal fluid

so measuring the concentrations of ADMA in cerebral spinal fluid after subarachnoid hemorrhage may be helpful in evaluating the development of delayed cerebral vasospasm.