Bolter C P
Department of Physiology, University of Otago, Dunedin, New Zealand.
Acta Physiol Scand. 1994 Aug;151(4):421-8. doi: 10.1111/j.1748-1716.1994.tb09764.x.
Intrinsic cardiac regulation, the direct effect of changes in right atrial pressure on heart rate, was examined in rabbits under chloralose/urethane anaesthesia. Autonomic influences on the cardiac pacemaker were eliminated by cervical vagotomy and intravenous propranolol. Right atrial transmural pressure was monitored as the difference between right atrial and pleural pressures. Blood volume expansion (5-15%) increased right atrial transmural pressure and heart rate and produced a sinus arrhythmia associated with respiration-linked fluctuations in right atrial transmural pressure. The gain of intrinsic cardiac rate regulation was calculated as 0.96 +/- 0.24 beats min-1 mmHg-1 at a heart rate of 218 +/- 6 beats min-1 (values as the mean +/- SEM, n = 12). When heart rate was reduced by electrical stimulation of the peripheral end of the right vagus nerve, gain increased to 2.25 +/- 0.57 and 4.61 +/- 1.6 beats min-1 mmHg-1 at heart rates of 180 +/- 4 and 130 +/- 4 beats min-1, respectively (n = 6 and n = 10; P < 0.05 compared with pre-stimulation values). During vagally-induced bradycardia, rapid infusion of blood into the left superior vena cava produced a brief marked cardiac acceleration. We conclude that right atrial pressure has a small direct influence on heart rate, and this is enhanced by background cardiac parasympathetic stimulation.
在水合氯醛/乌拉坦麻醉下，对家兔的心脏内在调节（即右心房压力变化对心率的直接影响）进行了研究。通过颈迷走神经切断术和静脉注射普萘洛尔消除自主神经对心脏起搏器的影响。将右心房跨壁压监测为右心房压力与胸膜压力之差。血容量扩充（5 - 15%）可增加右心房跨壁压和心率，并产生与右心房跨壁压呼吸相关波动有关的窦性心律失常。在心率为218 ± 6次/分钟时，心脏内在心率调节增益计算为0.96 ± 0.24次/分钟·毫米汞柱-1（数值为平均值 ± 标准误，n = 12）。当通过电刺激右迷走神经外周端使心率降低时，在心率分别为180 ± 4次/分钟和130 ± 4次/分钟时，增益分别增加到2.25 ± 0.57次/分钟·毫米汞柱-1和4.61 ± 1.6次/分钟·毫米汞柱-1（n = 6和n = 10；与刺激前值相比，P < 0.05）。在迷走神经诱导的心动过缓期间，快速向左上腔静脉输血可产生短暂的明显心脏加速。我们得出结论，右心房压力对心率有较小的直接影响，并且这种影响在背景性心脏副交感神经刺激下会增强。
