Abstract: Objective To observe the polymorphism of nitric oxide synthase(NOS)gene and the changes of nitric oxide(NO)in cerebral infarct.Methods The prospective case-control study was employed.Cases contained 193 subjects with cerebral infarction of internal carotid artery system within 2 weeks.Controls contained 103 subjects which came from the normal health checkup.The polymorphism in intron 4 of endothelial nitric oxide synthase(eNOS)gene were detected.NO content was measured by Griess diazotization assay and NOS activity by enzynatic assay.Results There were 48 subjects with allele a in intron 4 of eNOS gene(eNOS4a)in cases and 12 in controls.The frequencies of eNOS4a in cases was higher than that in controls(χ²=8.86,P=0.003).Multivariate Logistic regression analysis confirmed that eNOS4a was an independent risk factors for cerebral infarction(P=0.032).NO production and NOS activity were 6.04(3.83～11.49)μmol/L,(2.97±1.47)U/ml,respectively in cases,and 6.89(4.64～12.43)μmol/L,(3.16±1.46)U/ml,respectively in controls.NO production in cases were significantly lower than that in controls(P=0.022).There was not differential in NOS activity between these two groups(P=0.517).NO production and NOS activity were 5.07(3.18～7.62)μmol/L,(2.77±1.13)U/ml,respectively in the subjects with eNOS4a,and 6.89(4.64～12.43)μmol/L,(3.12±1.54))U/ml,respectively in the subjects without eNOS4a.NO production in the subjects with eNOS4a were significantly lower than that in the subjects without eNOS4a(P=0.001).The NOS activities were not significantly different in subjects with or without eNOS4a(P=0.100).Conclusion eNOS4a possibly exerted some effects on cerebral infarction by diminishing NO.

Key words: nitric oxide, endothelial nitric oxide synthase, gene, polymorphism, cerebral infarction