Aim To observe the changes of PKGIa mRNA and protein expressive level in cerebral arterial smooth muscle cells(CASMC)induced by bloody cerebrospinal(BCSF)in rats,and to investigate the value of PKGIa signaling pathway in cerebral vasospasm(CVS)after subarachnoid hemorrhage(SAH).Methods The pure CASMC were cultured by tissue-sticking methods.Semi-quantitative reverse transcription and polymerase chain reaction(RT-PCR)were used to examine the PKGIa mRNA expression after CASMC were exposed to BCSF for 24 h and 48h respectively.And PKGIa protein expressions were determined by Western blotting.The changes of CASMC proliferation were determined by MTT and 3H-TdR incorporated way.Results BCSF could stimulate CASMC proliferating.The mRNA and protein of PKGIa could be detected in all groups,and the expressive level of mRNA and protein had a possible relationship with CASMC prolferation.Conclusion The results suggested that PKGIa signaling pathway might play an important role in the CVS after SAH.