Watson-Wright W, Boudreau G, Cardinal R, Armour J A
Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
Am J Physiol. 1991 Nov;261(5 Pt 2):R1269-75. doi: 10.1152/ajpregu.1991.261.5.R1269.
The augmentation of cardiac inotropism induced by electrical stimulation of acutely decentralized efferent preganglionic sympathetic axons is reduced after the administration of timolol into the major ipsilateral intrathoracic ganglia. Thus it has been proposed that, in addition to nicotinic synapses, beta-adrenergic ones exist in intrathoracic ganglia that are involved in the efferent sympathetic regulation of the mammalian heart. Whether these are beta 1- as opposed to beta 2-adrenoceptor subtypes is unknown. In the present series of experiments, acutely decentralized canine efferent preganglionic sympathetic axons were stimulated before and after the administration of beta 1 (atenolol)- or beta 2 (ICI 118551)-selective adrenoceptor antagonists into the ipsilateral stellate and middle cervical ganglia to determine whether beta 1- or beta 2-adrenoceptors exist in intrathoracic ganglia that are involved in cardiac regulation. Augmentations of right and left ventricular inotropism induced by efferent preganglionic sympathetic axon stimulation were attenuated when either agent was administered into the major ipsilateral intrathoracic sympathetic ganglia. Myocardial liberation of norepinephrine evoked by these stimulations was also reduced after intraganglionic administration of either agent. These data indicate that canine intrathoracic neurons contain beta 1- and beta 2-adrenoceptors that are involved in the efferent sympathetic regulation of the heart.
将噻吗洛尔注入同侧主要胸段神经节后，由急性离断的传出节前交感神经轴突电刺激所诱导的心肌收缩力增强作用减弱。因此，有人提出，除了烟碱样突触外，胸段神经节中还存在β-肾上腺素能突触，它们参与哺乳动物心脏的传出交感神经调节。这些是β1 - 而非β2 - 肾上腺素能受体亚型尚不清楚。在本系列实验中，在将β1（阿替洛尔）或β2（ICI 118551）选择性肾上腺素能受体拮抗剂注入同侧星状神经节和颈中神经节之前和之后，对急性离断的犬传出节前交感神经轴突进行刺激，以确定参与心脏调节的胸段神经节中是否存在β1或β2肾上腺素能受体。当将任何一种药物注入同侧主要胸段交感神经节时，由传出节前交感神经轴突刺激所诱导的右心室和左心室收缩力增强作用均减弱。在神经节内注入任何一种药物后，这些刺激所诱发的去甲肾上腺素心肌释放也减少。这些数据表明，犬胸段神经元含有参与心脏传出交感神经调节的β1和β2肾上腺素能受体。
