Prince of Wales Medical Research Institute, Sydney, Australia.
J Physiol. 2010 Feb 15;588(Pt 4):701-12. doi: 10.1113/jphysiol.2009.185348. Epub 2010 Jan 5.
Elevated muscle sympathetic nerve activity (MSNA) features in many cardiovascular diseases, but how this sympathoexcitation is brought about differs across pathologies. Unitary recordings from post-ganglionic muscle vasoconstrictor neurones in human subjects have shown that the augmented MSNA in the obstructive sleep apnoea syndrome (OSAS) is associated with an increase in firing probability and mean firing rate, and an increase in multiple within-burst firing. Here we characterize the firing properties of muscle vasoconstrictor neurones in patients with chronic obstructive pulmonary disease (COPD), who are chronically asphyxic. We tested the hypothesis that this elevated chemical drive would shift the firing pattern from that seen in healthy subjects to that seen in OSAS. The mean firing probability (52%) and mean firing rate (0.92 Hz) of 17 muscle vasoconstrictor neurones recorded in COPD were comparable to those previously recorded in OSAS (51% and 0.96 Hz), but significantly higher than those recorded in a group of healthy subjects with high levels of resting MSNA (35% and 0.33 Hz). In COPD single neurones fired once in 63% of cardiac intervals, comparable to OSAS (59%), but significantly lower than in the healthy group (78%). Conversely, single neurones fired twice in 25% of cardiac intervals, similar to OSAS (27%), but significantly higher than in the healthy group (18%). We conclude that the chronic asphyxia associated with COPD results in an increase in the firing probability and mean firing frequency of muscle vasoconstrictor neurones and causes a shift towards multiple firing, reflecting an increase in central muscle vasoconstrictor drive.
肌肉交感神经活动（MSNA）升高的特征存在于许多心血管疾病中，但这种交感兴奋在不同的病理情况下是如何产生的却有所不同。在人体节后血管收缩神经元的单一记录中已经表明，阻塞性睡眠呼吸暂停综合征（OSAS）中的增强的 MSNA 与发射概率和平均发射率的增加以及爆发内多次发射的增加有关。在这里，我们描述了患有慢性阻塞性肺疾病（COPD）的患者的肌肉血管收缩神经元的发射特性，这些患者长期处于窒息状态。我们检验了这样一个假设，即这种升高的化学驱动力会将发射模式从健康受试者的模式转变为 OSAS 中的模式。在 COPD 中记录的 17 个肌肉血管收缩神经元的平均发射概率（52%）和平均发射率（0.92 Hz）与之前在 OSAS 中记录的相似（51%和 0.96 Hz），但明显高于在一组具有高静息 MSNA 的健康受试者中记录的（35%和 0.33 Hz）。在 COPD 中，单个神经元在 63%的心脏间隔中发射一次，与 OSAS 相似（59%），但明显低于健康组（78%）。相反，单个神经元在 25%的心脏间隔中发射两次，与 OSAS 相似（27%），但明显高于健康组（18%）。我们的结论是，与 COPD 相关的慢性窒息导致肌肉血管收缩神经元的发射概率和平均发射频率增加，并导致多次发射的转变，反映了中枢肌肉血管收缩驱动的增加。
