Courtice G P, McCloskey D I
J Comp Physiol B. 1985;155(5):571-5. doi: 10.1007/BF00694446.
Hearts of toads (Bufo marinus) were perfused in situ with oxygenated Ringer's solution. The flow of the perfusate was varied during periods of vagal stimulation and in the absence of vagal stimulation. Pulse interval and cardiac contraction were monitored, and results only from those animals that showed no change in pulse interval with changes in flow in the absence of vagal stimulation were used. In these animals, during vagal stimulation, cardiac slowing was greater when flow was low than when it was high. In addition, in cases where vagal stimulation caused atrio-ventricular block, the block could be reversed by an increase in flow of the perfusate. The results are consistent with flow through the heart being an important determinant of the concentration of neurally released ACh at the pacemaker sites and therefore of the effectiveness of the vagus nerve.
用含氧的任氏液对海蟾蜍（Bufo marinus）的心脏进行原位灌注。在迷走神经刺激期间和无迷走神经刺激时，改变灌注液的流量。监测脉搏间期和心脏收缩情况，仅使用那些在无迷走神经刺激时流量变化而脉搏间期无变化的动物的结果。在这些动物中，迷走神经刺激期间，流量低时心脏减慢比流量高时更明显。此外，在迷走神经刺激导致房室传导阻滞的情况下，灌注液流量增加可使阻滞逆转。这些结果与流经心脏的流量是神经释放的乙酰胆碱在起搏点部位浓度的重要决定因素，因此也是迷走神经有效性的重要决定因素这一观点一致。
