Koizumi K, Terui N, Kollai M, Brooks C M
Proc Natl Acad Sci U S A. 1982 Mar;79(6):2116-20. doi: 10.1073/pnas.79.6.2116.
Simultaneous recording of activity in the vagal and sympathetic supplies to the heart has revealed that in reflexly and centrally evoked activity these two "antagonists" do not necessarily change action reciprocally. Coactivation occurs in chemoreceptor reflexes and related reactions, upon stretching of the sinoatrial nodal region of the right atrium and when certain hypothalamic regions are stimulated. The objective of the present work was to assay the physiological importance of coactivation of the two potentially antagonistic cardiac nerves in anesthetized dogs. Output from the heart was monitored by recording volume flow in the thoracic aorta just below the aortic arch; cardiac contractility was measured as left ventricular dp/dt. Tape recordings of vagus and sympathetic nerve activity during chemoreceptor and baroreceptor reflexes, during reciprocal and nonreciprocal changes produced by hypothalamic stimulation, and during hypoxia and hypercapnia were used to trigger stimulators feeding a stimulus per action potential to cardiac vagus and sympathetic nerves after central connections were cut. The vagus stimulation alone produced a decrease in aortic blood flow; stimulation of the sympathetic nerve alone resulted in increased aortic blood flow. Simultaneous stimulation of vagus and sympathetic, however, produced an even greater cardiac output (measured by aortic blood flow). Intermediate degrees of heart rate and strength of myocardial contraction were maintained in coactivation. Obviously, an association of increased vagus and sympathetic actions, which can be effected reflexly or by action of higher centers, is of physiological benefit. In control reactions that relate cardiac function to body need, both reciprocal and synergistic actions (coactivation) of cardiac nerves are used.
同时记录迷走神经和交感神经对心脏的活动显示，在反射性和中枢性诱发的活动中，这两种“拮抗剂”并不一定相互反向改变作用。在化学感受器反射及相关反应、右心房窦房结区域受牵拉时以及刺激某些下丘脑区域时会发生共同激活。本研究的目的是测定麻醉犬中两条潜在拮抗的心脏神经共同激活的生理重要性。通过记录主动脉弓下方胸主动脉的容积流量来监测心脏输出；以左心室dp/dt来测量心脏收缩力。利用化学感受器和压力感受器反射期间、下丘脑刺激产生的反向和非反向变化期间以及低氧和高碳酸血症期间迷走神经和交感神经活动的磁带记录，在切断中枢连接后触发刺激器，向心脏迷走神经和交感神经每一个动作电位馈送一个刺激。单独刺激迷走神经会使主动脉血流量减少；单独刺激交感神经会使主动脉血流量增加。然而，同时刺激迷走神经和交感神经会产生更大的心输出量（通过主动脉血流量测量）。共同激活时维持了中等程度的心率和心肌收缩力。显然，迷走神经和交感神经作用增强的关联，可通过反射或高级中枢的作用实现，具有生理益处。在将心脏功能与身体需求相关联的对照反应中，心脏神经的反向和协同作用（共同激活）均会被利用。
