Objectives: To investigate the relationship between G-protein beta(3) subunit (GNB(3)) gene polymorphism and essential hypertension, insulin resistance and obesity.
Methods: Fasting plasma glucose (FPG), fasting insulin (Ins), lipid profile, and fibrinogen (Fib) were determined by convenient methods and the polymorphism of GNB(3) was detected by PCR-RFLP and sequencing in 376 individuals 187 first generation offsprings of hypertensives and 189 first generation offsprings of nonhypertensives in Daqing, China. The relationship between GNB(3) polymorphism and hypertension, insulin resistance was analyzed by univariate correlation analysis, and multivariate regression analysis with SAS software package.
Results: (1) The frequency of CT/TT genotype of GNB(3) C825T was significantly higher in the first generation offsprings of the hypertensives than in the first generation offsprings of nonhypertensives (0.78:0.69, P = 0.06). (2) The insulin sensitivity index [IAI = 1/(FPG x FINS)] in the CT and TT genotype groups was significantly lower than that in the group with CC genotype. The blood pressure and BMI were significantly higher than those of the CC genotype. (3) IAI was correlated negatively with SBP in CT/TT genotype group (r = -0.3519, P = 0.0001), whereas this correlation was not significant in the CC genotype group (r = -0.0055, P = 0.931). The patients were divided into 2 groups according to the median of IAI. In the group with the IAL higher than the median (LnIAI = -5.0016 +/- 0.1830) the SBP of the CT/TT genotype carriers was significantly higher than that of the CC genotype carriers (146 +/- 1.84 mm Hg vs 132 +/- 5.19 mm Hg, P < 0.05). In the group with the IAI lower than the median [IAI(2) = -4.1625 +/- 0.3716] the SBP of the CT/TT genotype carriers was not significantly different from that of the CC genotype carriers (136 +/- 2.4 mm Hg vs 133 +/- 2.0 mm Hg, P > 0.05). The comparison of diastolic pressure showed the similar result. (4) IAI had negatively correlation with SBP in CT/TT genotype carriers without hypertensive family history after controlling age and sex (r = -0.4864 P = 0.001), however, such correlation was not found in CC genotype carriers.
Conclusion: CT and TT genotype of GNB(3) C825T was correlated with insulin sensitivity, blood pressure, and BMI. GNB(3) C825T gene enhances the hypertensive effect of insulin resistance.