Clinical And Basic Research On Correlation Factors Of Difference Antihypertensive Effect By Metoprolol

Objective: 1. To approach the influence of CYP2D6 andβ1 adenoreceptor gene polymorphism and acquired factors to antihypertensive effect of different dose metoprolol in hypertensive patients after adjust dose by therapeutic effect.2. To approach the baseline blood pressure, activity of renin and concentration of renin angiotensinâ…¡in blood plasm, expression of myocardialβ1-AR gene,β1-adrenoceptor gene methylation state to antihypertensive effect of metoprolol in SHRs which have identical genotype.Methods: In the part of clinical research, 136 hypertensive were administrated with metoprolol, 25mg/day at beginning, then adjusted to 100mg/day or 200mg/day according to blood pressure and adverse effect, dose would not be adjusted any more if patients took metoprolol 200mg/day. Acquired characteristics of patients were gained before the research. Chain reaction-restriction fragment length polymorphism (PCR-RFLP) and Polymerase chain reaction (PCR) were applied to detect CYP2D6 andβ1 adenoreceptor gene polymorphism after 8-week follow-up visit.In the part of experimental research, forty-five Spontaneously Hypertensive Rats(SHR) were randomly divided into metoprolol group (50mg/kg/d) and normal saline control group. Blood pressures were measured, then dose was adjusted according to blood weight every week. After 4 week intervention, myodardium and common carotid artery blood were gained. SHR in metoprolol group were divided into utility and ineffective group according to blood pressure. Using gene sequencing to checkβ₁-AR genotype at first; radioimmunity was applied to detect activity of renin and concentration of renin angiotensinâ…¡in blood plasm; realtime-PCR was used for myocardial mRNA expression ofβ₁-AR gene; MSP and sulfite sequencing were applied to detect methylated status inβ₁-AR gene.Results: 1. 128 patients finished clinical research and effective power of metoprolol is 53.1 % . Monofactorial analysis shows that patients with different CYP2D6*10 genotype(P<0.05), Gly389Arg ofβ₁-AR genotype(P<0.05), BMI (P<0.05), baseline diastolic blood pressure(P<0.01)have inequality effective power. Subgroup analysis: Monofactorial analysis of 25mg/d group shows that the patients with different CYP2D6*10 genotype(P<0.01), CYP2D6*2 genotype(P< 0.05), Gly389Arg ofβ₁--AR genotype(P<0.05), baseline diastolic blood pressure(P<0.05)have inequality effective power. Monofactorial analysis of 100mg/d group shows that patients with different CYP2D6*10 genotype(P < 0.01), baseline diastolic blood pressure(P < 0.01)have inequality effective power. Monofactorial analysis of 200mg/d group shows that patients with different CYP2D6*10 genotype(P < 0.05), Gly389Arg ofβ₁-AR genotype, age(P<0.05), BMI (P<0.01) have inequality effective power.2. Results for multifactoring regression analysis: the significance level of final factors entering into the Logistic regression equation was BMI, Gly389Arg ofβ₁-AR genotype, dose and baseline DBP. Its accurating rate to predict antihypertensive effect after adjust dose by therapeutic effect of metoprolol was 89.8%.3. After 4 weeks intervention, 36 SHR finished experimental research, blood pressure in metoprolol group is 163.0±7.0mmHg, which significantly lower than 163.0±7.0mmHg in control group(P<0.01).β₁-AR genotype is identical in metoprolol group and effective power of metoprolol is 53.1%.4. The baseline blood pressure of SHR in utility and ineffective group are 187.2±6.3mmHg, 177.5±9.4mmHg respectively(P < 0.01). activity of renin and concentration of renin angiotensin II in blood plasm have no defference between utility and ineffective group(P>0.05). expression of myocardialβ₁-AR gene in utility and ineffective group are 21.2±50.5, 8.2±13.2 respectively(P < 0.05). Bioinformatic analysis demonstrates that there are methylation modification situs inβ₁-AR gene of both human and rat, but MSP and sulfite sequencing are fail to confirm SHRβ₁-AR gene DNA have methylation in metoprolol group.Conclusions: 1. Hypertensive patients need different dose of metoprolol individuality. CYP2D6*10 and Arg389Gly ofβ₁AR, BMI and baseline diastolic blood pressure are the most significantly influential factors to metoprolol, but those factors cannot totally explain antihypertensive effect.2. CYP2D6 andβ₁-AR gene polymorphism, baseline diastolic blood pressure are the most significantly influential factors to 25mg/d and 100mg/d metoprolol. Age, BMI only influence antihypertensive effect of 200mg/d metoprolol. CYP2D6*1*1 genotype,β₁-ARArg389Arg genotype, normal BMI and old patients with ineffection of 100mg/d can add to 200mg/d.3. There are different antihypertensive effect of metoprolol in SHR with identicalβ₁-AR genotype. The baseline blood pressure and expression of myocardialβ₁-AR gene are the most significantly influential factors to metoprolol. MSP and sulfite sequencing are fail to confirm SHRβ₁-AR gene DNA have methylation in metoprolol group.