Associaton of polymorphism of endothelial nitric oxide synthase gene with essential hypertension and type 2 diabetes mellitus

Objective To investigate the association of the polymorphism of endothelial nitric oxide synthase (eNOS) gene 27bp variable number of tandem repeats (VNTR) with essential hypertension (EH) and type 2 diabetes mellitus (DM) in Chinese population. Methods (1) Genotypes were determined by polymerase chain reaction (PCR)-agarose gel electrophoresis. (2) Fasting serum nitric oxide metabolites (NOx) were measured by nitrate reductase. (3) During oral glucose tolerance test (OGTT) serum immunoreactive insulin (IRI) and C peptide (CP) were measured by radioimmunoassay. Results (1) The frequenciesofaalleleinEHandtype2DMgroupwere significantly higher than that in control group (0.109 vs 0.051; 0.129vs 0.051, P0.05). The frequency of aa+ab genotype in type 2 DM group was significantly higher than that in control group (0.224 vs 0.103, P0.05). (2) Fasting serum NOx in aa+ab genotype was significantly lower than that in bb genotype of control group (P0.05). (3) In EH group, serum IRI and CP during OGTT in aa+ab genotype were all higher than those in bb genotype. Among them, serum IRI and CP at fasting, 30 min, 180 min and serum CP at 120 min showed significant differences between aa+ab and bb genotypes (P0.01 or P0.05). Whereas in type 2 DM group, serum IRI and serum CP at 30 min, 60 min in aa+ab genotypes during OGTT were higher than those in bb genotype, only serum IRI at 30 min, 60 min and serum CP at 60 min showed significant differences between aa+ab and bb genotypes (P0.01 or P0.05). (4) The HOMA-IR of aa+ab genotype was significantly higher than that of bb genotype in EH group (P0.05). Conclusion The polymorphism of eNOS gene 27bp VNTR is associated with EH and type 2 DM in Chinese population. It is suggested that a allele may be involved in the etiology of EH by reducing basal NO release of endothelium and also involved in the etiology of EH and type 2 DM by insulin resistance.