氯胺酮对培养心肌细胞的直接作用及其机制

Effects of ketamine on rat ventricular myocytes of primary culture and its mechanism

目的 研究氯胺酮对培养心肌细胞的直接作用及其机制。方法 分离 SD乳鼠心室肌细胞培养 4～ 5天 ,分别加入终浓度为 0、10、4 0和 160 μg/ ml的氯胺酮作用 2 .5小时。测定细胞搏动功能、心肌酶活性 ( L DH和 CK)、细胞存活率、细胞内静息 Ca2 +以及加入 5 0 mmol/ L 氯化钾激发经细胞膜电压门控的 Ca2 + 通道内流的瞬息 Ca2 + 。结果 10 μg/ ml氯胺酮对心肌细胞搏动频率及强度无明显影响 ,>4 0μg/ ml时细胞搏动明显减慢减弱 ,达 160μg/ ml则心肌细胞酶 L DH和 CK活性明显增加 ,细胞存活率下降。氯胺酮在各实验浓度呈剂量依赖性抑制 K+ 激发的 Ca2 + 内流 ,超临床剂量降低细胞内静息 Ca2 +。结论 临床剂量氯胺酮对心肌细胞直接作用不明显 ,高浓度呈现负性变时和变力效应 ,超高剂量甚至产生心肌细胞毒性作用。通过抑制细胞膜电压门控 Ca2 +通道的 Ca2 +内流 ,降低细胞内Ca2 + ,是氯胺酮负性变时和变力作用机制之一。

Objective To study the direct effects of ketamine on rat ventricular myocytes of primany culture and its mechanism.Methods Four or five day old primary culture ventricular myocytes obtained from SD rats were treated with ketamine at final concentration of 0,10,40 or 160μg/ml for 2.5hours,respectively.The contractility,myocardial enzymes (LDH and CK)activities,cell survival rate,quiescent intracellular Ca 2+ level and transient intracellular Ca 2+ level via influx through voltage gated calcium channels activated by potassium were measured.Results Ketamine had no significant effects on the cellular contractility,myocardial enzymes activities and cell survial rate at the concentration of 10μg/ml or 40μg/ml,respectively,however,at high concentration (40μg/ml and 160μg/ml),produced negative inotropic and chronotropic effects and at 160μg/ml increased myocardial enzymes activities and decreased cell survival rate.At the various concentrations,ketamine inhibited the transient Ca 2+ influx by potassium in dose dependent manner,only at high concentration,decreased intracellular quiescent Ca 2+ level.Conclusion At clinical concentration,ketamine has no significant effects,at supraclinical concentration produces negative chronotropic and inotropic and even toxic effects on ventricular myocytes.Decrease of intracellular Ca 2+ level via inhibiting Ca 2+ influx through voltage gated channels is one of the mechanism of ketamines negative chronotropic and inotropic effects.