Gotoh Taro Miyahara, Fujiki Nobuhiro, Matsuda Tomoko, Gao Shuang, Morita Hironobu
Department of Physiology, Gifu University School of Medicine, 40 Tsukasa-Machi, Gifu 500-8705, Japan.
Am J Physiol Regul Integr Comp Physiol. 2004 Jan;286(1):R25-30. doi: 10.1152/ajpregu.00458.2003. Epub 2003 Sep 18.
Gravity acts on the circulatory system to decrease arterial blood pressure (AP) by causing blood redistribution and reduced venous return. To evaluate roles of the baroreflex and vestibulosympathetic reflex (VSR) in maintaining AP during gravitational stress, we measured AP, heart rate (HR), and renal sympathetic nerve activity (RSNA) in four groups of conscious rats, which were either intact or had vestibular lesions (VL), sinoaortic denervation (SAD), or VL plus SAD (VL + SAD). The rats were exposed to 3 G in dorsoventral axis by centrifugation for 3 min. In rats in which neither reflex was functional (VL + SAD group), RSNA did not change, but the AP showed a significant decrease (-8 +/- 1 mmHg vs. baseline). In rats with a functional baroreflex, but no VSR (VL group), the AP did not change and there was a slight increase in RSNA (25 +/- 10% vs. baseline). In rats with a functional VSR, but no baroreflex (SAD group), marked increases in both AP and RSNA were observed (AP 31 +/- 6 mmHg and RSNA 87 +/- 10% vs. baseline), showing that the VSR causes an increase in AP in response to gravitational stress; these marked increases were significantly attenuated by the baroreflex in the intact group (AP 9 +/- 2 mmHg and RSNA 38 +/- 7% vs. baseline). In conclusion, AP is controlled by the combination of the baroreflex and VSR. The VSR elicits a huge pressor response during gravitational stress, preventing hypotension due to blood redistribution. In intact rats, this AP increase is compensated by the baroreflex, resulting in only a slight increase in AP.
重力作用于循环系统，通过引起血液重新分布和减少静脉回流来降低动脉血压（AP）。为了评估压力感受性反射和前庭交感神经反射（VSR）在重力应激期间维持动脉血压中的作用，我们在四组清醒大鼠中测量了动脉血压（AP）、心率（HR）和肾交感神经活动（RSNA），这四组大鼠分别为完整大鼠、有前庭损伤（VL）的大鼠、去窦弓神经（SAD）的大鼠或前庭损伤加去窦弓神经（VL + SAD）的大鼠。通过离心使大鼠在背腹轴上承受3G的重力作用3分钟。在两种反射均无功能的大鼠（VL + SAD组）中, 肾交感神经活动没有变化，但动脉血压显著下降（与基线相比为-8±1 mmHg）。在压力感受性反射功能正常但无前庭交感神经反射（VSR）的大鼠（VL组）中，动脉血压没有变化，肾交感神经活动略有增加（与基线相比为25±10%）。在有前庭交感神经反射（VSR）功能但无压力感受性反射的大鼠（SAD组）中，观察到动脉血压和肾交感神经活动均显著增加（动脉血压为31±6 mmHg，肾交感神经活动为87±10%与基线相比），表明前庭交感神经反射（VSR）在重力应激时会引起动脉血压升高；在完整大鼠组中，这些显著的升高被压力感受性反射显著减弱（动脉血压为9±2 mmHg，肾交感神经活动为38±7%与基线相比）。总之，动脉血压由压力感受性反射和前庭交感神经反射（VSR）共同控制。前庭交感神经反射（VSR）在重力应激期间引发巨大的升压反应，防止因血液重新分布导致的低血压。在完整大鼠中，这种动脉血压升高被压力感受性反射所代偿，导致动脉血压仅略有升高。
Zotero 插件