【摘要】 实验采用标准玻璃微电极细胞内记录技术记录心肌细胞动作电位（action potential,AP）、肌力换能器记录心肌收缩力（force contraction,Fc）,研究乙酰胆碱（acetylcholine,ACh）对离体豚鼠心房肌、心室肌的作用。结果表明,10μmol/L ACh可缩短心房肌、心室肌动作电位的时程（action potential duration,APD）。心房肌APD在给药前后分别为208.57±36.05ms及101.78±14.41ms（n=6,P<0.01）,心室肌APD在给药前后分别为286.73±36.11ms及265.16±30.06 ms（n=6,P<0.01）。心房肌动作电位的幅度（action potential amplitude,APA）也降低,给药前后分别为88.00±9.35 mV及62.62±20.50 mV（n=6,P<0.01）,而心室肌APA无明显变化。ACh还降低心房肌、心室肌的收缩力,心房肌、心室肌Fc的抑制率分别为100％（n=6,P<0.01）和37.57±2.58％（n=6,P<0.01）。ACh对心房肌、心室肌APD和Fc的抑制作用在一定范围内（1nmol/L～100μmol/L）随ACh浓度的增高而增强。用Scott法求出ACh对心房肌、心室肌APD缩短作用的KD值,分别为0.275和0.575μmol/L,对Fc抑制作用的KD值分别为0.135和0.676μmol/L。各浓度下ACh对心房肌效应与心室肌效应作组间t检验,从10nmol/L到0.1mmol/L均有显著的统计学差异。此外,10μmol/L阿托品及20mmol/L更多还原

【Abstract】 The purpose of this study was to investigate the different effects of ACh on the action potential and force contraction in guinea pig atrial and ventricular myocardium by using standard microelectro-des and force transducer. The results showed that the duration of the action potential ( APD) of atrial myocardium was shortened from 208. 57±36. 05 to 101. 78±14. 41 ms (n = 6, P < 0. 01) , and the APD of the ventricular myocardium was shortened from 286. 73±36. 11 to 265. 16±30. 06 ms ( n = 6, P < 0. 01). The amplitude of the action potential ( APA) of the atrial myocardium was decreased from 88. 00 ±9. 35 to 62. 62±20. 50 mV (n = 6, P < 0. 01) , while the APA of the ventricular myocardium did not change significantly. The force contraction of atrial myocardium was inhibited completely (n=6, P < 0. 01) , while the force contraction of ventricular myocardium was inhibited by 37. 57±2. 58% (n=6,P <0. 01). The ACh effects correlated with its concentration. The KD of the APD shortening effects in the atrial and ventricular myocardium were 0. 275 and 0. 575 μmol/L. The KD of the negative inotropic in the atrial and ventricular myocardium were 0. 135 and 0. 676 μmol/L, respectively. The corresponding data points were compared using t test between the atrial and ventricular myocardium, and the differences were significant when the ACh concentration was above 10 nmol/L. Furthermore, atropine ( 10 μmol/L) and CsCl (20 mmol/L) blocked the effects of 10 μmol/L ACh on the APD of ventricular myocardium, while CdCl2(0. 1 mmol/L) had no influence on these effects. In conclusion, ACh could shorten the action potential duration and inhibit the force contraction of atrial and ventricular myocardium in a concentration-dependent manner. There are differences in the effects of ACh on the atrial and ventricular myocardium. The atrial myocardium is more sensitive to ACh than the ventricular myocardium. It is probable that the muscarinic receptor and the potassium channel, but not the calcium channel, are involved in the ACh-induced shortening of the ventricular APD.更多还原