CHANGES IN THE NEURAL DRIVE TO ABDOMINAL EXPIRATORY MUSCLES IN HEMORRHAGIC HYPOTENSION
CHANGES IN THE NEURAL DRIVE TO ABDOMINAL EXPIRATORY MUSCLES IN HEMORRHAGIC HYPOTENSION
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DOI：
10.1152/ajpheart.1994.266.6.h2423
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发表时间：
1994-06-01
影响因子：
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通讯作者：
FREGOSI, RF
中科院分区：
文献类型：
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作者：
FREGOSI, RF
本研究的目的是验证失血性低血压增加对氯醛糖-尿素麻醉猫腹部呼气肌的神经驱动的假说，该假说是在恒定的动脉二氧化碳分压(PaCO2)和高氧条件下进行的。第二个目的是详细描述吸入肺通气量(VI)的伴随变化以及在这些条件下的呼吸模式。在中度和重度出血性低血压时，记录到矫正和积分的外斜肌和腹直肌肌电(EMG)和VI，平均血压分别下降30%和60%。通过向吸入的混合气体中添加二氧化碳和氧气，防止了PaCO2的下降，并将动脉血氧分压维持在高氧水平(>；200 mm Hg)。在中、重度低血压时，VI分别增加2.5倍和5倍(P<；0.05)。VI的变化完全是通过潮气量的变化来调节的，这表明反射不会改变呼吸节律产生结构的活动。对照组和中、重度低血压组的外斜肌肌电值分别为2、44和100%，腹直肌的相应肌电值分别为10、28和100%(P<；0.05)。双侧颈迷走神经切断术导致对出血的呼吸反应降低一到三倍，并消除了腹肌肌电活动的增加。总而言之，出血性低血压反射性地增加了肺通气量和对腹肌的神经驱动。这种反射是由迷走神经调节的，但受体的位置尚未确定。
The purpose of this study was to test the hypothesis that hemorrhage-induced hypotension increases the neural drive to the abdominal expiratory muscles in chloralose-urethan-anesthetized cats that are studied under conditions of constant arterial Pco(2) (Pa-co2) and hyperoxia. A secondary aim was to describe in detail the concomitant changes in inspired pulmonary ventilation (VI) and the pattern of breathing under these conditions. The rectified and integrated electromyogram (EMG) of the external oblique and rectus abdominis muscles and VI were recorded in moderate and severe hemorrhagic hypotension, leading to reductions in mean blood pressure of similar to 30 and 60%, respectively. The Pa-co2 was prevented from falling, and the arterial PO2 was maintained at a hyperoxic level (> 200 mmHg) by adding CO2 and O-2 to the inspired gas mixture. VI increased by 2.5- and 5-fold in moderate and severe hypotension (P < 0.05). The changes in VI were mediated exclusively by changes in tidal volume, indicating that the reflex did not alter the activity of respiratory rhythm-generating structures. The EMG of external oblique muscles averaged 2, 44, and 100% in control conditions and in moderate and severe hypotension, respectively; corresponding values in rectus abdominis muscles were 10, 28, and 100% (P < 0.05 for both muscles). Bilateral cervical vagotomy caused a one- to threefold decrease in the ventilatory response to hemorrhage and abolished the increase in abdominal muscle EMG activities. In conclusion, hemorrhagic hypotension reflexly increases pulmonary ventilation and the neural drive to the abdominal muscles. The reflex is vagally mediated, but the location of the receptors was not identified.