Abstract: ObjectiveTo explore the relationships among atrial natriuretic peptide (ANP) and cerebral vasospasm (CVS) following subarachnoid hemorrhage (SAH) and hyponatremia.MethodsPlasma ANP levels and serum natrium and blood flow rate of intracal major arterial were assessed at different times (1 to 3 days, 7 days and 14 days after SAH) in 42 patients with SAH. Correlation analysis was carried out among plasma ANP, blood sodium level and blood flow rate of intracal major arterial.Results28 patients had CVS. Plasma ANP levels in CVS patients significantly elevated compared with non-CVS and control subjects (P<0.05). Hyponatremia in CVS patients also significantly elevated compared with non-CVS subjects (P<0.05). Plasma ANP level had significant negative relationship with serum natrium level at the 7th day and 14th day (r2=-0.778,r3=-0.653;P<0.01,P<0.05) in SAH patients. Plasma ANP level had significant positive correlation with middle cerebral artery mean flow velocity on the 7th day (r3=0.702,P<0.05) in SAH patients. Middle cerebral artery mean flow velocity had significant negative relationship with serum natrium level on the 7th day and 14th day (r2=-0.693,r3=-0.653 , both P<0.05) in SAH patients.ConclusionANP might cause hyponatremia following SAH and play an important role in pathogenesis of earlier period CVS.

Key words: subarachnoid hemorrhage, atrial natriuretic peptide, hyponatremia, cerebral vasospasm, transcranial Doppler