The Study Of Optimal Treatment Plan In Hypertensives With Anti-AT1-Receptor Autoantibodies And Its Mechanism

Partâ… Candesartan versus Imidapril Comparative Trial in Hypertensives with Anti-AT1-Receptor AutoantibodiesA Stepwise Drug Treatment,Randomized,Blinded Assignment,Open-label,Parallelgroup, Multicenter Clinical TrialObjectives Angiotensinâ…¡and anti-AT1-receptor autoantibodies(AT1-AAs) are very important for the development of hypertension,and several antihypertensive drugs target these factors.Our aim was to determine whether AT1-AAs were related to the blood pressure lowering effect of angiotension receptor blockers(ARBs) in hypertensive target therapy.Methods The candesartan versus imidapril comparative trial in hypertensives with AT1-AAs was a multicenter,randomized,blinded assignment,open-label,parallelgroup comparison clinical trial in 7 centers of Wuhan,China.511 patients with moderate-to-severe primary hypertension were randomized to treatment with the candesartan-based regimens or the imidapril-based regimens for 8 weeks.AT1-AAs were detected by ELISA method.According to the AT1-AA,patients were divided into positive or negative group of AT1-AA after therapy end.Results The mean blood presure(BP) reduction in AT1-AA-positive hypertensives was lower in candesartan-based regimen subgroup than in imidapril-based regimen subgroup(SBP/DBP:-35.9/17.6 mmHg and -28.8/13.4 mmHg,respectively,P＜0.01). In contrast,the blood pressure response in the AT1-AA-negative subjects was equal between the candesaran subgroup and the imidapril subgroup(p＞0.05).The mean SBP was higher in the AT1-AA-positive group than in the AT1-AA-negative group at random entry(mean SBP:160.5±16.5 and 156.2±17.7mmHg,respectively;P=0.03); blood pressure was well controlled with both treatment-based regimens due to achieve BP control trial.The percentage of the AT1-AA-positive imidapril-treated patients who received other antihypertensive drugs was larger than that of the AT1 -AA-positive candesartan-treated patients(94%and 86%,respectively;P＜0.05).In addition,no relation was seen between the titer of AT1-AA and blood pressure response to candesartan.Conclusions We found that AT1-AA was associated with the BP lowering response to candesartan,and confirmed that AT1-AA was a risk factor of hypertension.The findings offer a new tailoring treatment approach using AT1-AA to predict the hypertensive target therapy. Partâ…¡Influence of the Anti-AT1-Receptor Autoantibodies on Cytosolic Free Calcium Concentration in Adult Rat Ventricular MyocytesObjectives To study the effects of anti-AT1-receptor autoantibodies on dynamic changes of cytosolic free calcium concentration in isolated adult rat left ventricular myocytes.Methods The peptide corresponding to the sequence of the second extracellular loop of rat AT1 receptor was synthesized by solid-phase peptide synthesis technique.The peptide was used as the antigen to immunize Wistar rats,and then the anti-AT1-receptor antibody was isolated from serum sample by saturated ammonium sulfate precipitation,and then purified by a CNBr-activated sepharose 4B affinity chromatography column.The quantity,purity,and concentration of the purified antibodies were analyzed by Bradford method,SDS-PAGE and ELISA respectively,and the antibodies were used to prove the affinity with AT1-receptor in the rat ventricular myocytes by immunocytochemistry.By using laser scanning confocal microscope,the[Ca²⁺]_i fluorescence signal change in isolated rat left ventricular myocytes was investigated by loading with[Ca²⁺]_i indicator fluo-3/AM,and four groups were divided:(1) Angâ…¡group;(2) anti-AT1 receptor autoantibody group;(3) anti-AT1 receptor autoantibody+ losartan group;(4) control group.Results Anti-AT1-receptor autoantibodies were detected in immunized rats 2 weeks after immunization,with the titers gradually increasing in the first 8 weeks.0.3mg purified anti-AT1-receptor autoantibodies could be obtained from 10ml sera.Angâ…¡caused a large transient spiking of[Ca²⁺]_i which followed by a rapid decrease in[Ca²⁺]_i (157.4%±52.5%),while in anti-AT1-receptor autoantibody group,we observed a sustained elevated in[Ca²⁺]_i after the transient spiking like Angâ…¡group(164.0%± 34.0%,compared with Angâ…¡group,p＞0.05);and the effect was partly antagonized by losartan(79.7%±13.2%,compared with the anti-AT1-receptor autoantibody group,p＜0.05).Conclusions Both Angâ…¡and anti-AT1-receptor autoantibodies could elevated[Ca²⁺]_i concentration of adult rat ventricular myocytes.But the effect of anti-AT1-receptor autoantibodies was more sustained,and could be attenuated by AT₁ receptor antagonist, and it is also suggest that ventricular myocytes of rat respond to anti-AT1-receptor autoantibodies with a increase of[Ca²⁺]_i via an AT₁ receptor,and the changes of[Ca²⁺]_i mainly depend on the release of intracellular stores.