Objectives: To search for association between heart period signal spectrum features and single nucleotide polymorphisms at five sites of inducible nitric oxide synthase(iNOS

NOS2) and endothelial nitric oxide synthase(ecNOS

NOS3) of NOS2 G-954C

NOS2 C-1173T

NOS3 T-786C

NOS3 A-922G and NOS3 G894T in the Chinese Han nationality population.Methods: Genomic DNA from 166 individuals(female 77 and male 89

age 62.40±2.5 yrs) selected randomly from Chinese Han nationality population as research objects was obtained.The SNPs of NOS2 G-954C

NOS2 C-1173T

NOS3 T-786C

NOS3 A-922G and NOS3 G894T were genotyped by allele-specific primer(ASP) PCR technique.The allelic genotypes of five sites SNPs of NOS2 and NOS3 were determined by clustering analysis technique.The analytical software for spectral features of heart period signal(HPS) was applied to determine the spectral parameters of heart period signal in the groups.Results: The spectral parameters of HPS

including absolute ultra-low frequency power(AUP)

relative ultra-lower frequency power(RPU)

ratio of AUP to AHP(RUH)

absolute high frequency power(APH)

relative high frequency power(RPH) and total power value(TPV)

were not significantly different between the groups with GG genotypes and with GC allelic genotypes of NOS2 G-954C(P>0.05).Among the above parameters of HPS spectrum

only RPH in the group with CC genotypes was significantly lower than that in the group with TT allelic genotypes of NOS2 C-1173T(P<0.05=.There was no significant difference in the parameter values of HPS spectrum among the group with TT

TC or CC allelic genotypes of NOS3 T-786C(P>0.05).No significant difference in the parameter values of HPS spectrum was noted among the groups with AA

AG or GG allelic genotypes of NOS3 A-922G(P>0.05).The comparison of the above HPS parameters showed that only APH was significantly lower than that in the group with TT allelic genotypes of NOS3 G894T(P<0.01=.Conclusion: The TT allelic genotype of NOS2 C-1173T is associated with the increase of RPH and TT allelic genotype of NOS3 G894T is associated with the increase of APH in the HPS parameters.This suggests that single nucleotide polymorphisms of NOS2 C-1173T and NOS3 G894T may be the further causes of the variability of HPS spectral parameters.