兔心脏节前交感神经元的功能选择性。
Functional selectivity of cardiac preganglionic sympathetic neurones in the rabbit heart.
机构信息
Department of Cardiovascular Sciences, University of Leicester, UK.
Department of Cardiovascular Sciences, University of Leicester, UK; University of Birmingham, UK.
出版信息
Int J Cardiol. 2018 Aug 1;264:70-78. doi: 10.1016/j.ijcard.2018.03.119. Epub 2018 Mar 27.
BACKGROUND
Studies have shown regional and functional selectivity of cardiac postganglionic neurones indicating there might exist a similar heterogeneity in spinal segmental preganglionic neurones, which requires further investigation.
METHODS
Right and left sympathetic chains were electrically stimulated from T6 to T1 in the innervated isolated rabbit heart preparation (n = 18). Sinus rate, left ventricular pressure, retrograde ventriculo-atrial conduction, monophasic action potential duration, effective refractory period, ventricular fibrillation threshold and electrical restitution were measured.
RESULTS
Right sympathetic stimulation had a greater influence on heart rate (T1-T2: right; 59.9 ± 6.0%, left; 41.1 ± 5.6% P < 0.001) and left stimulation had greater effects on left ventricular pressure (T1-T2: right; 20.7 ± 3.2%, left; 40.3 ± 5.4%, P < 0.01) and ventriculo-atrial conduction (T1-T2: right; -6.8 ± 1.1%, left; -15.5 ± 0.2%) at all levels, with greater effects at rostral levels (T1-T3). Left sympathetic stimulation caused shorter monophasic action potentials at the base (T4-T5: right; 119.3 ± 2.7 ms, left; 114.7 ± 2.5 ms. P < 0.05) and apex (T4-T5: right; 118.8 ± 1.2 ms, left; 114.6 ± 2.6 ms. P < 0.05), greater shortening of effective refractory period (T4-T5: right; -3.6 ± 1.3%, left; -7.7 ± 1.8%. P < 0.05), a steeper maximum slope of restitution (T4-T5 base: right; 1.3 ± 0.2, left; 1.8 ± 0.2. P < 0.01. T4-T5 apex: right; 1.0 ± 0.2, left; 1.6 ± 0.3. P < 0.05) and a greater decrease in ventricular fibrillation threshold (T4-T5: right; -22.3 ± 6.8%, left;-39.0 ± 1.7%), with dominant effects at caudal levels (T4-T6).
CONCLUSIONS
The preganglionic sympathetic efferent axons show functionally distinct pathways to the heart. The caudal segments (T4-T6) of the left sympathetic chain had a greater potential for arrhythmia generation and hence could pose a target for more focused clinical treatments for impairments in cardiac function.
背景
研究表明，心脏节后神经元具有区域性和功能选择性，这表明脊髓节前神经元可能存在类似的异质性，这需要进一步研究。
方法
在受神经支配的离体兔心标本中，从 T6 到 T1 电刺激右和左交感神经链（n=18）。测量窦性心率、左心室压力、逆行房室传导、单相动作电位时程、有效不应期、心室颤动阈值和电复律。
结果
右交感刺激对心率的影响更大（T1-T2：右，59.9%±6.0%；左，41.1%±5.6% P<0.001），而左刺激对左心室压力（T1-T2：右，20.7%±3.2%；左，40.3%±5.4% P<0.01）和房室传导（T1-T2：右，-6.8%±1.1%；左，-15.5%±0.2%）的影响更大，在头端水平（T1-T3）影响更大。左交感刺激引起基底（T4-T5：右，119.3±2.7 ms；左，114.7±2.5 ms P<0.05）和顶点（T4-T5：右，118.8±1.2 ms；左，114.6±2.6 ms P<0.05）单相动作电位缩短，有效不应期缩短（T4-T5：右，-3.6%±1.3%；左，-7.7%±1.8% P<0.05），最大复律斜率更陡（T4-T5基底：右，1.3±0.2；左，1.8±0.2 P<0.01；T4-T5顶点：右，1.0±0.2；左，1.6±0.3 P<0.05），心室颤动阈值降低（T4-T5：右，-22.3%±6.8%；左，-39.0%±1.7%），在尾端水平（T4-T6）作用更明显。
结论
节前交感传出轴突对心脏有功能不同的途径。左交感神经链的尾段（T4-T6）有更大的心律失常发生潜力，因此可能成为心脏功能障碍更有针对性的临床治疗靶点。
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