Danilo P, Rosen M R, Hordof A J
Circ Res. 1978 Nov;43(5):777-84. doi: 10.1161/01.res.43.5.777.
We determined the effects of acetylcholine on automaticity of isolated cardiac Purkinje fibers from neonatal and adult dogs and on the idioventricular rhythm of adult dogs with complete atrioventricular block. Isolated Purkinje fibers were studied with standard microelectrode techniques during superfusion with Tyrode's solution at 37 degrees C. For both age groups, spontaneous rate was decreased by acetylcholine, an effect which was reduced by atropine. The magnitude of the effect is equal in both neonatal and adult dogs. The negative chronotropic effect of acetylcholine was not prevented by phentolamine, indicating that an alpha-adrenergic mechanism was not involved. The idioventricular rate of conscious dogs with formalin-induced heart block was decreased by administration of acetylcholine. The effect was augmented by propranolol and attenuated by atropine. Thus, for both the in vitro and in situ ventricular specialized conducting system, acetylcholine decreases automaticity presumably through combination with a muscarinic receptor.
我们测定了乙酰胆碱对新生犬和成年犬离体心脏浦肯野纤维自律性的影响，以及对成年完全性房室传导阻滞犬心室自主节律的影响。采用标准微电极技术，在37℃用台氏液灌流的条件下，对离体浦肯野纤维进行研究。对于这两个年龄组，乙酰胆碱均可降低自发频率，阿托品可减弱此效应。新生犬和成年犬的效应强度相同。酚妥拉明不能阻止乙酰胆碱的负性变时效应，表明其不涉及α-肾上腺素能机制。给甲醛诱导的心脏传导阻滞清醒犬静脉注射乙酰胆碱可降低心室自主节律。普萘洛尔可增强此效应，阿托品可减弱此效应。因此，对于体外和在体的心室特殊传导系统，乙酰胆碱可能是通过与毒蕈碱受体结合来降低自律性。
