天门冬氨酸对心室复极和室性心律失常的影响

The impact of NMDA on ventricular repolarization and ventricular arrhythmias

目的研究腹腔注射天门冬氨酸(NMDA)对心室复极和室性心律失常诱发的影响。方法将36只成年Wistar大鼠随机分为对照组(CTL组)、NMDA组(N组)、NMDA+NMDA的受体拮抗剂MK-801组(N+M组),分别连续10d腹腔给予生理盐水、NMDA、NMDA+MK-801。记录体表心电图(II导联),并在Langerdorff灌流下行程控电刺激,记录左室前壁基底部(LAB)、前壁心尖部(LAA)、后壁基底部(LPB)和后壁心尖部(LPA)复极过程,测量单向动作电位时程(MAPD)和有效不应期(ERP),及其离散度,计算室性心律失常诱发率和频率阈值。结果与CTL组比较,N组PR间期、QT间期和QTc间期延长,心率增快;左室20%、复极三角和90%的复极时间(MAPD20、triangulation、MAPD90)延长,ERP/MAPD90较小;心室复极离散度增加[COVMAPD90:(0.153±0.017)vs(0.034±0.003),COVERP:(0.242±0.018)vs(0.078±0.009),P均<0.01];室性心律失常诱发率增加(100%vs 16.7%,P均<0.01)。而MK-801减弱了NMDA对心室复极和室性心律失常诱发的影响。结论慢性注射NMDA将延长心室复极时程,增加复极离散度和室性心律失常的易感性。

Objective To investigate the impact of chronic NMDA injection on ventricular repolarization and ventricular arrhythmias. Methods Thirty-six Wistar rats were randomly divided into control group （ CTL group）, NMDA group （ N group ） and NMDA＋MK-801 group （N＋M group）, underwent intraperitoneal administration with 0.9% saline NMDA, NM- DA and MK-801 for 10 days respectively. We performed surface II ECG, and then conducted S1 S2 at four left ventricle sites in Langerdroff-perfused state, The monophasic action potentials duration （MAPD） and effective refractory period （ERP） were measured, their dispersion and the susceptibility of ventricular arrhythmias were calculated. Results Compared with CTL group, N group showed longer PR, QT and QTc interval, and faster heart rate. The MAPD2o, triangulation and MAPDg0 were increased, ERP/MAPDgo was decreased, and the lager spatial dispersion of repolarization [ COVMAPDgo ： （0. 153 ±0. 017 ） VS （0. 034±0. 003 ）, COVERP ： （0. 242±0. 018 ） VS （0. 078±0. 009）, all P〈0.01 ], and higher incidence of ven- tricular arrhythmias was displayed in N group（ 100% vs 16.7% ,P〈0. O1 ）. MK-801 withstands the effect of NMDA on left ventricle repolarization and ventricular arrhythmogenesis. Conclusion Chronic injection with NMDA increased the dura- tion and dispersion of left ventricle repolarization, which may relate to high susceptibility of ventrieular arrhythmias.