Hypertension and coronary artery disease

Relationship between CYP17A1 genetic polymorphism and coronary artery disease in a Chinese Han population

BACKGROUND

CYP17A1 gene encodes P450c17 proteins, which is a key enzyme that catalyzes the formation of sex hormones. Many clinical studies showed that sex hormones levels play an important role in the pathogenesis of coronary artery disease (CAD). However, the relationship between CYP17A1 genetic polymorphisms and CAD remains unclear. The aim of this study was to investigate the association of CYP17A1 genetic polymorphisms with CAD in a Han population of China.

METHODS

A total of 997 people include 490 patients and 507 controls were selected for the present study. Five single-nucleotide polymorphisms (SNPs) (rs4919686, rs1004467, rs4919687, rs10786712, and rs2486758) were genotyped by using the real-time PCR (TaqMan) method.

RESULTS

For men, the rs10786712 was found to be associated with CAD in a recessive model (P=0.016), after adjustment of the major confounding factors, the significant difference was retained (OR=1.644, 95% confidence interval [CI]: 1.087-2.488, P=0.019). For women, the rs1004467 was also found to be associated with CAD in a dominant model (P=0.038), the difference remained statistically significant after multivariate adjustment (OR=1.623, 95% CI: 1.023-2.576, P=0.040). The distribution of rs4919687 genotypes showed a significant difference between CAD and control participants in a recessive model (P=0.019), the significant difference was retained after adjustment for covariates (OR=0.417, 95% CI: 0.188-0.926, P=0.032).

CONCLUSION

Rs1004467, rs4919687, rs10786712 of CYP17A1 gene are associated with CAD in Han population of China. The TT genotype of rs10786712 could be a protective genetic marker of CAD in men. The CC genotype of rs1004467 and the AA genotype of rs4919687 could be risk genetic markers of CAD in women. However, large sample size study including other SNPs of CYP17A1 should be performed in future studies.

Coronary hemodynamics in aging spontaneously hypertensive and normotensive Wistar-Kyoto rats

OBJECTIVE

To delineate hypertension-related and age-related changes in coronary hemodynamics and to assess the role of myocardial (i.e. left ventricular) hypertrophy and cardiac fibrosis in inducing progressive deterioration of coronary flow reserve associated both with hypertension and with aging.

METHODS

Systemic and coronary hemodynamics (using radionuclide-labeled microspheres), right ventricular, left ventricular, and aortic mass indexes, and ventricular hydroxyproline concentrations (an estimate of collagen) in normotensive Wistar-Kyoto and spontaneously hypertensive rats aged 22, 35, and 65 weeks were determined.

RESULTS

Spontaneously hypertensive rats of all ages had greater left ventricular and aortic masses, greater collagen concentrations in both ventricles, a lower coronary flow reserve, and greater minimal coronary vascular resistance after administration of dipyridamole than did Wistar-Kyoto rats. Despite spontaneously hypertensive rats having only left ventricular hypertrophy, coronary hemodynamics were impaired to the same extent in both ventricles. Progressive increases in myocardial collagen concentration, decreases in coronary flow reserve, and increases in minimal coronary vascular resistance were observed in rats of both strains with aging. A positive correlation and linear regression between myocardial collagen concentration and minimal vascular resistance were found for both ventricles of rats of both strains.

CONCLUSIONS

Both aging and hypertension adversely affected the coronary circulation; furthermore, these effects appeared to be additive. Cardiac fibrosis, but not hypertrophy, might play a role in progressive deterioration of coronary hemodynamics in aging and hypertension and could provide an explanation for the diastolic dysfunction encountered clinically in older patients with hypertension.