Hakumäki M O
Acta Physiol Scand. 1979 Oct;107(2):127-33. doi: 10.1111/j.1748-1716.1979.tb06451.x.
The influence of 42 i.v. infusions of saline on heart rate, sympathetic and vagal cardiac efferent activity and on the aortic baroreceptor and left atrial B-type nerve impulse activity was studied in 32 morphine-chloralose anesthetized dogs. The responses in heart rate were tachycardic in 31 infusions and bradycardic in 11 infusions. In tachycardia, sympathetic activity increased in a majority of the cases but also decreases and nonsignificant changes were observed. Vagal efferentation decreased in most of the cases but also nonsignificant changes or increases in activity occurred. Sympathetic efferentation mainly decreased in bradycardic responses while vagal efferentation diverged in different directions in its nerve activity rate. The ratio of sympathetic to vagal impulses significantly correlated to the heart rate in most of the cases in tachycardia but not in bradycardia. It is concluded that sympathetic and vagal cardiac efferentation plays a significant role in heart rate regulation in volume load-induced tachycardia but in bradycardia only the changes in sympathetic cardiac efferentation are important in respect to heart rate changes. The aortic baroreceptor and left atrial B-type receptor activity rate increased both in tachycardia and bradycardia. Changes in the activities of these receptors do not explain the different heart rate responses. It is supposed that bradycardic responses result from changes in cardiac contraction associated with some reflex mechanism suppressing the excitatory influence of the activity of atrial receptors on sympathetic cardiac efferentation.
在32只吗啡-氯醛糖麻醉的犬中，研究了42次静脉输注生理盐水对心率、交感和迷走神经心脏传出活动以及主动脉压力感受器和左心房B型神经冲动活动的影响。在31次输注中，心率反应为心动过速，11次输注中为心动过缓。在心动过速时，大多数情况下交感神经活动增加，但也有减少和无显著变化的情况。在大多数情况下迷走神经传出活动减少，但也有活动无显著变化或增加的情况。在心动过缓反应中，交感神经传出活动主要减少，而迷走神经传出活动在其神经活动速率上有不同方向的变化。在心动过速的大多数情况下，交感与迷走神经冲动的比率与心率显著相关，但在心动过缓时则不然。结论是，在容量负荷诱导的心动过速中，交感和迷走神经心脏传出活动在心率调节中起重要作用，但在心动过缓时，仅交感神经心脏传出活动的变化对心率变化很重要。在心动过速和心动过缓时，主动脉压力感受器和左心房B型受体的活动速率均增加。这些受体活动的变化并不能解释不同的心率反应。推测心动过缓反应是由心脏收缩的变化引起的，与某种反射机制有关，该机制抑制了心房受体活动对交感神经心脏传出活动的兴奋影响。
