Electrophysiology Study Of Losartan On Prevention To Atrial Fibrillation Of Rabbits Induced By Rappid Atrial Pacing

Objective To explore the effect of losartan on prevention to atria fibrillation ofrabbits induced by rapidly atria pacing.Materials and methods twenty-eight Newzealand white rabbits were randomlydivided into two groups: losartan group and control one. In losarton group, rabbitswere administered losartan at dosage of 15mg/(kg*d) by pouring into stomach with aplastic tube for 4 weeks, in control group, rabbits were administered biological salinewater. Electrode leads were localized into the fight atrium through internal jugularvein. After rappidly atria pacing at 700bpm for lh, AERP were recorded before andafter pacing. Burst S1S1 stimulation were used to induce atrial fibrillation (AF). Theinducibility to AF, AFCL and the time of AF sustained was recorded. The expressionlevelof of connexin45 and connexin40 mRNA in two groups is measured by real-timeFluorescent Quantitative RT Polymerase chain Reaction.Results①In losartan group, the shortened AERP after pacing were significantlyshorter than control group. (16.43±5.56ms vs 30.71±8.86ms,p＜0.01).②In losartangroup, the inducibility to Af were significantly less than controul group. (4/14 vs12/14, P=0. 006)③In losartan group, the time of atrial fibrillation sustained is shorterthan control group(47.5±9.6s vs 115.0±8.0 s, p＜0.001)④in losartan group, atrialfibrillation cycle length is longer than in control group (85.0±10.0ms vs 45.0±8.0ms,p＜0.001).⑤In losarton group, the value of CX45 mRNA is smaller thancontrol. (0.8762±0.0393 vs 0.6299±0.0228, P＜0.001)。⑥In losarton group, thevahe of Cx40 mRNA is smaller than in control one.(0.7623±0.0364 VS 0.5134±0.0394,P=0.008).Conclusions In view of electrophysiology and molecular biological study,losartan can effectively prevent the Af induced by rapiddly atria pacing.①Losartancan effectively prevent the shortening of AERP induced by rapidly atriapacing.②Losartan can effectively reduce the inducity of AF③Losartancan effectively longen AFCL④Losartan can effectively increase theexpression of gap junction protein connexins (connexin45, connexin40)mRNA.