利多卡因对低氧、酸中毒及肾上腺素条件下豚鼠左心室流出道心肌组织电活动的影响

Electrophysiological effects of lidocaine on myocardial tissue in guinea-pig left ventricular outflow tract under conditions of hypoxia,acidosis and treatment with epinephrine

目的:研究利多卡因对豚鼠左心室流出道心肌组织电活动的影响及其对该部位自律性异常的干预作用。方法:采用标准玻璃微电极细胞内电位记录技术,观测利多卡因对豚鼠左心室流出道自发慢反应电位的影响,以及利多卡因对无糖低O2、pH 6.8和肾上腺素(EPI)导致的该电位改变的影响。结果:(1)0.1、1、10μmol/L利多卡因可呈剂量依赖性地导致左心室流出道自发慢反应电位4相自动除极速度(VDD)、自发放电频率(RPF)和0相最大除极速度(Vmax)减慢,最大舒张电位(MDP)绝对值和动作电位幅度(APA)减小,复极50%和80%时间(APD50和APD80)缩短。(2)低O2可使VDD、RPF和Vmax减慢,MDP绝对值和APA减小,APD50缩短;和低O2灌流组相比,1μmol/L利多卡因+低O2可使VDD、RPF和Vmax进一步减慢,MDP绝对值增大,APA进一步降低。(3)pH 6.8的灌流液可使VDD、RPF和Vmax明显减慢,MDP绝对值增大,APA减小,APD50和APD80缩短;与pH6.8灌流组相比,pH 6.8的1μmol/L利多卡因可使VDD、RPF和Vmax进一步减慢,MDP绝对值进一步增大,APD50和APD80延长。(4)10μmol/L肾上腺素可使VDD、RPF和Vmax明显加快,MDP绝对值和APA增大,APD50和APD80缩短;1μmol/L利多卡因+10μmol/L EPI可使VDD和RPF减慢,MDP绝对值和APA减小,APD50和APD80延长。结论:利多卡因可降低豚鼠左心室流出道的自律性,同时对低O2、酸中毒和EPI所致的该部位自律性改变有一定的影响。

AIM： To study the electrophysiological effects of lidocaine on the myocardial tissue in guinea-pig left ventricular outflow tract under the conditions of hypoxia, acidosis and treatment with epinephrine. METHODS： The action potentials of pacemaker cells in guinea-pig left ventricular outflow tract were recorded by conventional technique with intracellular microelectrodes. The effects of lidocaine on the spontaneous slow response potentials were investigated under the conditions of hypoxia, acidosis and treatment with epinephrine （EPI）. RESULTS： Lidocaine markedly decreased the rate of pacemaker firing （RPF）, the velocity of diastolic depolarization （VDD）, the maximal rate of depolarization （Vm~, ）, the maximal diastolic potential （MDP） and the amplitude of action potential （APA）. Lidocaine also shortened the 50% and 80% of duration of action potential （ APD60 and APD80 ）. At the concentrations from 0.1μmol/L to 10 p.mol/L, the effects of lidocaine were more significant. Under the condition of hypoxia and perfusion with deprived glucose content for 15 min, VDD, RPF, V MDP and APA significantly decreased, and APD50 notably shortened. Under the condition of hypoxia, lidocaine at 1 μmol/L significantly decreased VDD, RPF, Vmax and APA as compared with the cells treated with hypoxia only. Perfusion with pH 6.8 solution for 10 min, VDD, RPF, Vmax and APA significantly decreased, MDP notably increased, and APD50 and APD80 markedly shortened. Under the condition of acidosis for 10 min, lidocaine significantly decreased VDD, RPF and Vmax, and lengthened APD50 and APD80 as compared with the cells under the condition of acido- sis alone. Perfusion with EPI at 10 μmol/L for 10 min resulted in significant increases in VDD, RPF, Vmax, MDP and APA, and notable shortenings of APDs0 and APDso were also observed. Compared with 10 ~mol/L EPI group, 1 i.rmol/L lidocaine ＋ 10 ~mol/L EPI significantly reduced VDD, RPF, MDP and APA, and lengthened APDso and APD80. CON- CLUSION： Lidocaine markedly decreases the autorhythmicity of the pacemaker cells in guinea-pig left ventricular outflow tract and influences the electrophysiological effects of hypoxia, acidosis and EPI.