Hohimer A R, Bissonnette J M, Machida C M, Horowitz B
Respir Physiol. 1985 Sep;61(3):327-34. doi: 10.1016/0034-5687(85)90075-1.
Fetal breathing movements (FBM) indicated by repetitive negative intrathoracic pressures and biparietal electrocorticograms (ECoG) were recorded from 8 fetal sheep for 3 h before (control) and 3 h after the administration of a carbonic anhydrase inhibitor, acetazolamide. FBM and the low voltage (LV) ECoG state occurred 36 +/- 5% (SEM) and 60 +/- 3% of the control period, respectively. Virtually no FBM occurred during high voltage (HV) ECoG while in 57 +/- 6% of the LV state the fetuses were making FBM. The peak magnitude of the negative intrathoracic (tracheal) pressure deflections was 4 +/- 1 Torr. Following acetazolamide the incidence of FBM rose to 53 +/- 4% (P less than 0.01) but there was no significant change in the incidence of the LV state (58 +/- 3%). Most of the increase in the incidence of FBM remained confined to periods of LV ECoG activity so that an increased proportion of this state (88 +/- 2%, P less than 0.001) was occupied with respiratory efforts. The amplitude of the FBM also increased to 8 +/- 1 Torr (P less than 0.05). The increased incidence and depth of FBM is most likely due to an elevated hydrogen ion concentration and differs from a fetal respiratory acidosis induced by increasing the inspired CO2 fraction to the ewe in that the respiratory stimulation induced by acetazolamide is not associated with an increased incidence of the permissive LV ECoG state.
通过重复性的胸腔内负压和双极皮质脑电图（ECoG）来指示胎儿呼吸运动（FBM），对8只胎羊在给予碳酸酐酶抑制剂乙酰唑胺之前（对照）和之后3小时进行记录。FBM和低电压（LV）ECoG状态在对照期分别出现36±5%（标准误）和60±3%的时间。在高电压（HV）ECoG期间几乎没有FBM发生，而在57±6%的LV状态下胎儿进行FBM。胸腔内（气管）负压偏转的峰值幅度为4±1托。给予乙酰唑胺后，FBM的发生率升至53±4%（P<0.01），但LV状态的发生率没有显著变化（58±3%）。FBM发生率的增加大部分仍局限于LV ECoG活动期，因此该状态中因呼吸努力而占有的比例增加（88±2%，P<0.001）。FBM的幅度也增加到8±1托（P<0.05）。FBM发生率和深度的增加很可能是由于氢离子浓度升高，并且与通过增加母羊吸入二氧化碳分数诱导的胎儿呼吸性酸中毒不同，因为乙酰唑胺诱导的呼吸刺激与允许性LV ECoG状态发生率的增加无关。
