Activation of the carotid body (CB) using intracarotid potassium cyanide (KCN) injection increases coronary blood flow (CoBF). This increase in CoBF is considered to be mediated by co-activation of both the sympathetic and parasympathetic nerves to the heart. However, whether cardiac sympathetic nerve activity (cardiac SNA) actually increases during CB activation has not been determined previously. We hypothesized that activation of the CB would increase directly recorded cardiac SNA, which would cause coronary vasodilatation. Experiments were conducted in conscious sheep implanted with electrodes to record cardiac SNA and diaphragmatic electromyography (dEMG), flow probes to record CoBF and cardiac output and a catheter to record arterial pressure. Intracarotid KCN injection was used to activate the CB. To eliminate the contribution of metabolic demand on coronary flow, the heart was paced at a constant rate during CB chemoreflex stimulation. Intra-carotid KCN injection resulted in a significant increase in directly recorded cardiac SNA frequency (from 24±2 to 40±4 bursts/minute; p<0.05) as well as a dose-dependent increase in mean arterial pressure (79±15 to 88±14 mmHg; p<0.01) and CoBF (75±37 Vs 86±42 mL/min; p<0.05). The increase in CoBF and coronary vascular conductance to intracarotid KCN injection was abolished after propranolol infusion, suggesting that the increased cardiac SNA mediates coronary vasodilatation. The pressor response to activation of the CB was abolished by pre-treatment with intravenous atropine but there was no change in the coronary flow response. Our results indicate that CB activation increases directly recorded cardiac SNA which mediates vasodilatation of the coronary vasculature.

中文翻译：

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在有意识的绵羊中，颈动脉体的激活增加了直接记录的心脏交感神经活动和冠状动脉血流量

使用颈动脉内氰化钾（KCN）注射激活颈动脉体（CB）可增加冠状动脉血流量（CoBF）。CoBF的这种增加被认为是通过交感神经和副交感神经与心脏的共激活介导的。但是，先前尚未确定在CB激活过程中心脏交感神经活动（心脏SNA）是否确实增加。我们假设CB的激活会增加直接记录的心脏SNA，这会导致冠状动脉舒张。实验是在有意识的绵羊中植入电极以记录心脏SNA和and肌肌电图（dEMG），流量探针以记录CoBF和心输出量以及导管以记录动脉压。颈动脉内KCN注射用于激活CB。为了消除代谢需求对冠状动脉血流的贡献，在CB化学反射刺激过程中，心脏以恒定的速度运动。颈内KCN注射导致直接记录的心脏SNA频率显着增加（从24±2增至40±4突发/分钟； p <0.05），并且平均动脉压呈剂量依赖性增加（79±15至88±14 mmHg; p <0.01）和CoBF（75±37 Vs 86±42 mL / min; p <0.05）。普萘洛尔输注后取消了颈动脉内KCN注射CoBF和冠状动脉血管电导的增加，这表明增加的心脏SNA介导了冠脉血管舒张。通过静脉内阿托品预处理可以消除对CB活化的压力反应，但冠状动脉血流反应没有变化。