Amorim Mateus R, Bonagamba Leni G H, Souza George M P R, Moraes Davi J A, Machado Benedito H
Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, 14049-900, SP, Brazil.
Exp Physiol. 2016 Nov 1;101(11):1359-1370. doi: 10.1113/EP085897.
What is the central question of this study? The arterial baroreflex regulates arterial pressure within a narrow range of variation. After sino-aortic denervation (SAD), rats show a large increase in arterial pressure variability, but mean arterial pressure levels remain similar to those of control rats. Considering that breathing influences the control of arterial pressure, the question is: to what extent does SAD cause changes in breathing? What is the main finding and its importance? Removal of arterial baroreceptors produced changes in breathing in rats, marked by a reduction in respiratory frequency, but not hypertension. These findings are indicative of a possible interaction of respiratory and autonomic neural mechanisms in the regulation of arterial pressure after SAD. Sino-aortic denervated (SAD) rats exhibit a mean arterial pressure (MAP) similar to that of control rats. Given that respiration modulates MAP, we hypothesized that conscious SAD rats show respiratory changes associated with the normal MAP. In this study, we evaluated the cardiovascular and respiratory activities and arterial blood gases in control and SAD rats. Male juvenile Wistar rats (postnatal day 19-21) were submitted to SAD, sham surgery or selective removal of the carotid bodies (CBX), and the three groups were evaluated 10 days after the surgery (SAD, n = 21; Sham, n = 18; and CBX, n = 13). The MAP in Sham, SAD and CBX groups was similar (P > 0.05), but the variability of MAP was significantly higher in SAD than in Sham and CBX rats (P < 0.0001). The duration of expiration and inspiration increased in SAD rats compared with Sham and CBX rats, which resulted in a reduced respiratory frequency and minute ventilation (P < 0.05). The arterial partial pressure of O and the haemoglobin saturation were reduced in SAD and CBX compared with Sham rats, whereas the arterial partial pressure of CO was increased in SAD compared with Sham rats. The short- and long-term respiratory variability were significantly higher in SAD than in Sham and CBX rats (P < 0.05). In addition, the reductions in MAP during deep breaths were greater in SAD than in Sham and CBX rats (P < 0.0001). The data show that SAD rats exhibit respiratory changes, which may be one of the compensatory mechanisms associated with the maintenance of normal levels of MAP in the absence of arterial baroreceptors.
本研究的核心问题是什么？动脉压力感受器反射在狭窄的血压变化范围内调节动脉血压。在进行主动脉弓去神经支配（SAD）后，大鼠的动脉血压变异性大幅增加，但平均动脉血压水平仍与对照大鼠相似。鉴于呼吸会影响动脉血压的控制，问题在于：SAD在多大程度上会引起呼吸变化？主要发现及其重要性是什么？去除动脉压力感受器会使大鼠的呼吸发生变化，其特征为呼吸频率降低，但不会导致高血压。这些发现表明，在SAD后动脉血压调节过程中，呼吸和自主神经机制之间可能存在相互作用。主动脉弓去神经支配（SAD）的大鼠表现出与对照大鼠相似的平均动脉血压（MAP）。鉴于呼吸会调节MAP，我们推测清醒的SAD大鼠会出现与正常MAP相关的呼吸变化。在本研究中，我们评估了对照大鼠和SAD大鼠的心血管和呼吸活动以及动脉血气。将雄性幼年Wistar大鼠（出生后第19 - 21天）进行SAD手术、假手术或选择性切除颈动脉体（CBX），并在手术后10天对三组进行评估（SAD组，n = 21；假手术组，n = 18；CBX组，n = 13）。假手术组、SAD组和CBX组的MAP相似（P > 0.05），但SAD组的MAP变异性显著高于假手术组和CBX组大鼠（P < 0.0001）。与假手术组和CBX组大鼠相比，SAD组大鼠的呼气和吸气持续时间增加，导致呼吸频率和分钟通气量降低（P < 0.05）。与假手术组大鼠相比，SAD组和CBX组的动脉血氧分压和血红蛋白饱和度降低，而与假手术组大鼠相比，SAD组的动脉血二氧化碳分压升高。SAD组的短期和长期呼吸变异性显著高于假手术组和CBX组大鼠（P < 0.05）。此外，深呼吸时SAD组大鼠的MAP降低幅度大于假手术组和CBX组大鼠（P < 0.0001）。数据表明，SAD大鼠表现出呼吸变化，这可能是在没有动脉压力感受器的情况下维持正常MAP水平的代偿机制之一。
