Study On The Changes Of Hemodynamic Characteristics Of ACE Gene D/I Polymorphism In Different Age Groups

Objective: Deletion/Insertion(D/I)polymorphism of the angiotensin converting enzyme(ACE)gene is associated with high risk of cardiovascular disease.While atherosclerosis is believed to be highly associated with atherosclerosis.This study aimed to investigate age-related changes in hemodynamics in association with different D/I polymorphism of ACE gene.We wish to provide primarily information in designing personalized exercise training programme,especially for young population,to delay the development of various cardiovascular diseases.Methods: 566 subjects,aged from 18-70 years old,were divided into five age-groups with a 10-year interval.Persons taking medicine for controlling of blood pressure and/or cholesterol level were excluded.Oral epithelial cells were collected from all subjects for determination of ACE genotypes using PCR.Thereafter,the subejects were divided into DD and DI/II groups.Blood samples of fasting venous blood were collected for measurement of viscosity.Peak systolic velocity(PSV)and end diastolic velocity(EDV)were measured on the common carotid artery using color doppler ultrasound.Thereafter,different parameters of hemodynamics :pulsatility pndex(PI),resistance index(RI),blood flow(Q)and wall shear stress(WSSmax)were calculated.Parameters of vascular structure and function:intimal-mediathickness(IMT)and maximum diameter(Dmax)were also measured.Systolic blood pressure(SBP)and diastolic blood pressure(DBP)were measured using electronic blood pressure monitor.Brachial-ankle wave velocity(ba PWV)and ankle-brachial index(ABI)were detected using the arteriosclerosis diagnostic apparatus.Waist-to-hip ratio,body mass index(BMI)and body fat rate were measured using body composition tester.SPSS 20.0 was used for statistical analysis of the data.Results :(1)Out of the 566 subjects,distribution of ACE genotype DD,DI and II was 13%,43% and 44%,respectively.The frequency of D allele was 34% and I allele 66%.These results are consistent with the Hardy-Weinberg equilibrium(P >0.05).(2)Blood viscosity did not change significantly following aging for either genotypes.Blood flow velocity and wall shear stress decreased significantly following aging from the age of 40-49 yr-old compared with the younger age groups(18-29 and 30-39 yr-old age group;P < 0.05).Nevertheless,changes in the 50-59yr-old age group and 60-70 yr-old age group were not as dramatic as the 40-49 yr-old age group.For DD genotype,the 40-59 yr-old age group had significantly lower PSV,EDV,and WSSmax(P < 0.05),but significantly higher PI and RI(P < 0.05)compared with the same age group in the DI/II genetype.(3)For both DD and DI/II genotype,results of blood pressure and ba PWV were at similar levels of the same age groups,and increased progressively following aging.By the age of 40-49 yr-old and following aging,results of the two parameters were significantly increased compared with younger age groups of both genotypes(P < 0.05).(4)Multi-way ANOVA analysis showed that WSSmax was significantly affected by age and PSV in both genotypes,and by interaction between EDV and age in the DD genotype(P < 0.05).Multivariate linear regression revealed that age was negatively correlated with WSSmax(r=-0.739,P < 0.05).Conclusions :(1)In this Han nationality,distributions of ACE genotype DD(13%),DI(43%),and II(44%)were similar as in the other areas in China.(2)In40-59 yr-old age group,DD genotype had lower blood flow velocity and wall shear stress,higher blood flow resistance,blood pressure,and arterial stiffness than DI/II genotype,thus a higher risk of developing cardiovascular disease than DI/II genotype.(3)Arterial stiffness increased significantly following aging and D/I polymorphism of ACE gene played minor role in it.(4)WSSmax can be used as a sensitive indicator of hemodynamics,as WSSmax was affected by age and PSV in both genotypes,and by interaction between EDV and age in DD genotype.