Ling L, Olson E B, Vidruk E H, Mitchell G S
Department of Comparative Biosciences, University of Wisconsin, Madison 53706, USA.
Respir Physiol. 1997 Aug;109(2):107-16. doi: 10.1016/s0034-5687(97)00045-5.
The purpose of this study was to test the hypothesis that carotid body-mediated, phrenic nerve responses to hypoxia are attenuated in adult rats that had been previously exposed to perinatal hyperoxia (one month of 60% O2; perinatal treated rats.) Integrated phrenic nerve responses to strictly controlled isocapnic hypoxia were measured in urethane-anesthetized, vagotomized, paralyzed and ventilated adult rats 2-5 months after perinatal hyperoxia, before and after bilateral carotid denervation. In untreated control rats, phrenic burst frequency, peak amplitude of integrated phrenic activity and minute phrenic activity increased 21 +/- 3 bursts/min (mean +/- SE), 158 +/- 20% and 279 +/- 34%, respectively, during hypoxia (50 Torr PaO2). In contrast, phrenic nerve activity increased to a significantly lesser degree in perinatal treated rats (frequency, 12 +/- 2 bursts/min; amplitude, 87 +/- 13%; minute activity, 150 +/- 19%; all P < 0.05). Hypoxic phrenic responses were abolished by carotid degeneration in both rat groups. In rats exposed to hyperoxia as adults, hypoxic phrenic responses were not attenuated versus untreated control rats. The data indicate that carotid body-mediated, isocapnic hypoxic chemoreflexes are impaired in perinatal treated rats, an effect unique to development. These effects cannot be accounted for by differences in blood gases (O2 or CO2) or pulmonary mechanics.
在先前暴露于围产期高氧环境（60%氧气，为期一个月；围产期处理组大鼠）的成年大鼠中，颈动脉体介导的膈神经对缺氧的反应会减弱。在围产期高氧暴露后2至5个月，对经氨基甲酸乙酯麻醉、迷走神经切断、麻痹并通气的成年大鼠，在双侧颈动脉去神经支配前后，测量其对严格控制的等碳酸性缺氧的膈神经综合反应。在未处理的对照大鼠中，缺氧（50 Torr PaO2）期间，膈神经爆发频率、膈神经活动综合峰值幅度和每分钟膈神经活动分别增加21±3次/分钟（平均值±标准误）、158±20%和279±34%。相比之下，围产期处理组大鼠的膈神经活动增加程度明显较小（频率为12±2次/分钟；幅度为87±13%；每分钟活动为150±19%；所有P<0.05）。两组大鼠的颈动脉变性均消除了低氧膈神经反应。在成年期暴露于高氧的大鼠中，与未处理的对照大鼠相比，低氧膈神经反应并未减弱。数据表明，围产期处理组大鼠中颈动脉体介导的等碳酸性低氧化学反射受损，这是一种发育特有的效应。这些效应不能用血气（氧气或二氧化碳）或肺力学的差异来解释。
