不同温度对离体大鼠心室肌单相动作电位、电兴奋性的影响
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摘要
目的观察不同温度对离体大鼠心室肌单相动作电位、电兴奋性的影响。方法 24只健康成年雄性SD大鼠随机分为C组、H1组、H2组各8只,腹腔注射麻醉后迅速开胸取出心脏,制备Langendorff离体心脏灌注模型,经K-H液平衡灌注15 min,C组继续灌注37℃的K-H液30 min,H1组继续灌注35℃的K-H液30 min,H2组继续灌注32℃的K-H液30 min。于平衡灌注末(T0)、继续灌注30 min(T1)时点记录HR及左心室前壁外膜层、中层、内膜层心肌心室肌单相动作电位(MAP),计算MAP复极90%的时程(MAPD90)。T1时行程控刺激并测量有效不应期(VERP)及电传导速度(CV)。另记录心律失常发生率。结果与同组T0时点、C组、H1组比较,H2组T1时点HR减慢(P均<0.05)。与同组T0时点比较,H2组T1时点外膜、中膜、内膜MAPD90延长(P均<0.05);与C组、H1组比较,H2组外膜、中膜、内膜MAPD90延长(P均<0.05)。与C组、H1组比较,H2组CV减慢、VERP延长(P均<0.05)。与C组、H1组比较,H2组心律失常发生率高(P均<0.05)。结论 37、35℃的温度对离体大鼠心脏MAP、电兴奋性无明显影响,而32℃低温可延长心室肌MAPD90、降低离体大鼠心脏电兴奋性,这可能是低温下心律失常发生风险增加的机制。
Objective To study the effects of different temperatures on monophasic action potential(MAP) and myocardial electrical excitability in isolated rat hearts.Methods Twenty-four healthy adult male SD rats were randomly divided into the groups C,H1,and H2.After intraperitoneal injection of anesthesia,the hearts were quickly removed and the Langendorff isolated heart perfusion model was prepared.The model was perfused with K-H solution for 15 minutes,and then the rats in the group C continued to be perfused with 37 ℃ K-H solution for 30 min,the H1 group with 35 ℃ K-H solution and the H2 group with 32 ℃ K-H solution.Heart rate(HR) and MAP were recorded at the end of balanced perfusion(T0) and continuous perfusion of 30 min(T1).The time course of 90% repolarization of MAP(MAPD90) was calculated.The effective refractory period(VERP) and conduction velocity(CV) were measured at T1 by programmed electrical stimulation(PES).The incidence of arrhythmia was also recorded.Results Compared with T0,HR in the groups C,H1,and H2 decreased at T1(P<0.05).Compared with T0,the MAPD90 of epicardium,mid-layer myodardium and endocardium prolonged at T1 in the groupH2(P<0.05).Compared with the groups C and H1,the MAPD90 of epicardium,midlayer myodardium and endocardium prolonged at T1 in the groupH2(P<0.05).Compared with the groups C and H1,CV slowed down and VERP prolonged in the groupH2(P<0.05).Compared with the groups C and H1,the incidence of arrhythmia was higher in the groupH2(P<0.05).Conclusion Temperature at 37℃ and 35 ℃ has no significant effect on the MAP and electrical excitability of isolated rat hearts,but low temperature of 32 ℃ can prolong the MAPD90 of ventricular myocardium and decrease the electrical excitability of isolated rat hearts,and this may be the mechanism of increased risk of arrhythmia under low temperature.
Objective To study the effects of different temperatures on monophasic action potential(MAP) and myocardial electrical excitability in isolated rat hearts.Methods Twenty-four healthy adult male SD rats were randomly divided into the groups C,H1,and H2.After intraperitoneal injection of anesthesia,the hearts were quickly removed and the Langendorff isolated heart perfusion model was prepared.The model was perfused with K-H solution for 15 minutes,and then the rats in the group C continued to be perfused with 37 ℃ K-H solution for 30 min,the H1 group with 35 ℃ K-H solution and the H2 group with 32 ℃ K-H solution.Heart rate(HR) and MAP were recorded at the end of balanced perfusion(T0) and continuous perfusion of 30 min(T1).The time course of 90% repolarization of MAP(MAPD90) was calculated.The effective refractory period(VERP) and conduction velocity(CV) were measured at T1 by programmed electrical stimulation(PES).The incidence of arrhythmia was also recorded.Results Compared with T0,HR in the groups C,H1,and H2 decreased at T1(P<0.05).Compared with T0,the MAPD90 of epicardium,mid-layer myodardium and endocardium prolonged at T1 in the groupH2(P<0.05).Compared with the groups C and H1,the MAPD90 of epicardium,midlayer myodardium and endocardium prolonged at T1 in the groupH2(P<0.05).Compared with the groups C and H1,CV slowed down and VERP prolonged in the groupH2(P<0.05).Compared with the groups C and H1,the incidence of arrhythmia was higher in the groupH2(P<0.05).Conclusion Temperature at 37℃ and 35 ℃ has no significant effect on the MAP and electrical excitability of isolated rat hearts,but low temperature of 32 ℃ can prolong the MAPD90 of ventricular myocardium and decrease the electrical excitability of isolated rat hearts,and this may be the mechanism of increased risk of arrhythmia under low temperature.
引文
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[15]Salinas P,Lopez-de-sa E,Pena-conde L,et al.Electrocardiographic changes during induced therapeutic hypothermia in comatose survivors after cardiac arrest[J].World J Cardiol,2015,7(7):423-430.
[16]Jin SQ,Niu LJ,Deng CY,et al.Effect of temperature on the activation of myocardial KATP channel in guinea pig ventricular myocytes:a pilot study by whole cell patch clamp recording[J].Chin Med J(Engl),2006,119(20):1721-1726.
[17]Desplantez T,Grikscheit K,Thomas NM,et al.Relating specific connexin co-expression ratio to connexon composition and gap junction function[J].J Mol Cell Cardiol,2015,89(Pt B):195-202.
[18]Tse G,Wong ST,Tse V,et al.Monophasic action potential recordings:which is the recording electrode[J].J Basic Clin Physiol Pharmacol,2016,27(5):457-462.
[19]Jeong DU,Lim KM.The effect of myocardial action potential duration on cardiac pumping efficacy:a computational study[J].Biomed Eng Online,2018,17(1):79.
[20]Tse G.Mechanisms of cardiac arrhythmias[J].J Arrhythmia,2016,32(2):75-81.
[21]Haraguchi R,Ashihara T,Namba T,et al.Transmural dispersion of repolarization determines scroll wave behavior during ventricular tachyarrhythmias[J].Circ J,2011,75(1):80-88.
[2]Chhabra L,Devadoss R,Liti B,et al.Electrocardiographic changes in hypothermia:a review[J].Ther Hypothermia Temp Manag,2013,3(2):54-62.
[3]Hudzik B,Gasior M.J-waves in hypothermia[J].CMAJ,2017,189(47):E1461-E1461.
[4]Lam DH,Dhingra R,Conley SM,et al.Therapeutic hypothermiainduced electrocardiographic changes and relations to in-hospital mortality[J].Clin Cardiol,2014,37(2):97-102.
[5]李惠,高鸿,赵艳,等.低温联合右美托咪定对兔心肌单相动作电位的影响[J].中华麻醉学杂志,2015,35(4):419-422.
[6]杨烨,高鸿,谷宇.低温联合七氟醚对兔心肌单相动作电位及跨室壁复极离散度的影响[J].中华麻醉学杂志,2010,30(7):780-783.
[7]李惠,高鸿,赵艳,等.低温联合右美托咪定对家兔心室复极时程和CX43蛋白表达的影响[J].贵州医科大学学报,2017,42(3):275-278.
[8]Tse G,Yeo JM,Tse V,et al.Gap junction inhibition by heptanol increases ventricular arrhythmogenicity by reducing conduction velocity without affecting repolarization properties or myocardial refractoriness in langendorff-perfused mouse hearts[J].Mol Med Rep,2016,14(5):4069-4074.
[9]王贵龙,高鸿,王子君,等.不同浓度七氟醚对缺血-再灌注心肌单相动作电位影响[J].临床麻醉学杂志,2018(5):478-482.
[10]Tse G,Wong ST,Tse V,et al.Restitution analysis of alternans using dynamic pacing and its comparison with S1S2 restitution in heptanol-treated,hypokalaemic Langendorff-perfused mouse hearts[J].Biomed Rep,2016,4(6):673-680.
[11]Tse G,Hothi SS,Grace AA,et al.Ventricular arrhythmogenesis following slowed conduction in heptanol-treated,Langendorff-perfused mouse hearts[J].J Physiol Sci,2012,62(2):79-92.
[12]Ostadal P,Mlcek M,Kruger A,et al.Mild therapeutic hypothermia is superior to controlled normothermia for the maintenance of blood pressure and cerebral oxygenation,prevention of organ damage and suppression of oxidative stress after cardiac arrest in a porcine model[J].J Transl Med,2013,11(1):1-7.
[13]Ning J,Mo L,Yi B,et al.Therapeutic whole-body hypothermia protects remote lung,liver,and kidney injuries after blast limb trauma in rats[J].Anesthesiology,2016,124(6):1360-1371.
[14]Yang L,Zhao X,Liu L.Mild hypothermia in improving multiple organ dysfunction after cardiac arrest[J].World J Emergency Medicine,2009,1(3):196.
[15]Salinas P,Lopez-de-sa E,Pena-conde L,et al.Electrocardiographic changes during induced therapeutic hypothermia in comatose survivors after cardiac arrest[J].World J Cardiol,2015,7(7):423-430.
[16]Jin SQ,Niu LJ,Deng CY,et al.Effect of temperature on the activation of myocardial KATP channel in guinea pig ventricular myocytes:a pilot study by whole cell patch clamp recording[J].Chin Med J(Engl),2006,119(20):1721-1726.
[17]Desplantez T,Grikscheit K,Thomas NM,et al.Relating specific connexin co-expression ratio to connexon composition and gap junction function[J].J Mol Cell Cardiol,2015,89(Pt B):195-202.
[18]Tse G,Wong ST,Tse V,et al.Monophasic action potential recordings:which is the recording electrode[J].J Basic Clin Physiol Pharmacol,2016,27(5):457-462.
[19]Jeong DU,Lim KM.The effect of myocardial action potential duration on cardiac pumping efficacy:a computational study[J].Biomed Eng Online,2018,17(1):79.
[20]Tse G.Mechanisms of cardiac arrhythmias[J].J Arrhythmia,2016,32(2):75-81.
[21]Haraguchi R,Ashihara T,Namba T,et al.Transmural dispersion of repolarization determines scroll wave behavior during ventricular tachyarrhythmias[J].Circ J,2011,75(1):80-88.