Steele Andrew R, Berthelsen Lindsey F, Fraser Graham M, Phillips Devin B, Fuhr Desi P, Wong Eric Y L, Stickland Michael K, Steinback Craig D
Neurovascular Health Lab, Faculty of Kinesiology, Sport, & Recreation, University of Alberta, 1-059D Li Ka Shing Centre for Health Research Innovation, Edmonton, T6G 2E1, Canada.
Division of BioMedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada.
Clin Auton Res. 2021 Jun;31(3):443-451. doi: 10.1007/s10286-021-00784-8. Epub 2021 Feb 9.
Obstructive sleep apnea (OSA) is a common disorder (~ 4%) that augments sympathetic nerve activity (SNA) and elevates blood pressure. The relationship between sympathetic vasomotor outflow and vascular responsiveness, termed sympathetic neurovascular transduction (sNVT), has been sparsely characterized in patients with OSA. Therefore, we sought to quantify spontaneous sympathetic bursts and related changes in diastolic pressure.
Twelve participants with variable severities of OSA were recruited. We collected muscle sympathetic nerve activity (MSNA) (microneurography) and beat-by-beat diastolic pressure (finger photoplethysmography) during normoxia (FiO = 0.21) and hyperoxia (FiO = 1.0) to decrease MSNA burst frequency. MSNA burst sequences (i.e. singlets, doublets, triplets and quadruplets) were identified and coupled to changes in diastolic pressure over 15 cardiac cycles as an index of sNVT. sNVT slope for each individual was calculated from the slope of the relationship between peak responses in outcome plotted against normalized burst amplitude.
sNVT slope was unchanged during hyperoxia compared to normoxia (normoxia 0.0024 ± 0.0011 Δ mmHg total activity [a.u.] vs. hyperoxia 0.0029 ± 0.00098 Δ mmHg total activity [a.u.]; p = 0.14). sNVT slope was inversely associated with burst frequency during hyperoxia (r = -0.58; p = 0.04), but not normoxia (r = -0.11; p = 0.71). sNVT slope was inversely associated with the apnea-hypopnea index (AHI) (r = -0.62; p = 0.030), but not after age was considered.
We have demonstrated that the prevailing MSNA frequency is unmatched to the level of sNVT, and this can be altered by acute hyperoxia.
阻塞性睡眠呼吸暂停（OSA）是一种常见疾病（约4%），会增强交感神经活动（SNA）并升高血压。在OSA患者中，交感神经血管运动输出与血管反应性之间的关系，即交感神经血管转导（sNVT），鲜有研究。因此，我们试图量化自发性交感神经爆发及舒张压的相关变化。
招募了12名OSA严重程度各异的参与者。我们在常氧（FiO₂ = 0.21）和高氧（FiO₂ = 1.0）状态下收集肌肉交感神经活动（MSNA）（微神经ography）和逐搏舒张压（手指光电容积描记法），以降低MSNA爆发频率。识别MSNA爆发序列（即单峰、双峰、三峰和四峰），并将其与15个心动周期内舒张压的变化相联系，作为sNVT的指标。根据绘制的结果峰值反应与归一化爆发幅度之间关系的斜率，计算每个个体的sNVT斜率。
与常氧相比，高氧期间sNVT斜率无变化（常氧时每单位总活动的Δ mmHg为0.0024 ± 0.0011，高氧时为0.0029 ± 0.00098 Δ mmHg总活动 [a.u.]；p = 0.14）。高氧期间sNVT斜率与爆发频率呈负相关（r = -0.58；p = 0.04），但常氧时无此相关性（r = -0.11；p = 0.71）。sNVT斜率与呼吸暂停低通气指数（AHI）呈负相关（r = -0.62；p = 0.030），但在考虑年龄因素后则无此相关性。
我们已经证明，主要的MSNA频率与sNVT水平不匹配，急性高氧可改变这种情况。
