Hohimer A R, Bissonnette J M
Department of Obstetrics and Gynecology, Oregon Health Sciences University, Portland 97201.
Pediatr Res. 1991 May;29(5):483-6. doi: 10.1203/00006450-199105010-00013.
Hypoxemia transiently inhibits the incidence of fetal breathing movements (FBM), but their incidence returns to normal after several hours despite maintained hypoxemia. We hypothesized that the lactic acidosis associated with prolonged systemic hypoxemia might mediate the adaptation of the hypoxemic inhibition of FBM. In sheep fetuses, the incidence of FBM was measured in a control hour and during 6 h of i.v. infusion of L-lactic acid, which raised the blood lactate concentrations to levels seen with moderate hypoxemia. FBM were observed at the same incidence as during control during each of the first 4 h (all approximately 40%). In the 5th h of lactic acid infusion, fetal hypoxemia was induced by lowering maternal inspired oxygen fraction and FBM occurred only 8 +/- 1% (SEM) of that hour. In a subsequent normoxemic recovery hour, the incidence of FBM remained below control levels. In the same animals on a different day, a similar hypoxemia induced without the acid infusion caused a comparable inhibition of FBM, but the incidence of FBM returned to the control level in a subsequent recovery hour. A moderate peripheral lactic acidosis does not blunt the inhibition of FBM evoked by acute hypoxemia and is not a likely explanation for the return of FBM during prolonged hypoxemia but actually might mediate some of the inhibition.
低氧血症会短暂抑制胎儿呼吸运动（FBM）的发生率，但即便低氧血症持续存在，数小时后其发生率会恢复正常。我们推测，与长期全身性低氧血症相关的乳酸酸中毒可能介导了低氧血症对FBM抑制作用的适应性变化。在绵羊胎儿中，在一个对照小时以及静脉输注L-乳酸6小时期间测量FBM的发生率，输注L-乳酸会使血乳酸浓度升高至中度低氧血症时的水平。在最初4小时的每一小时内，观察到的FBM发生率与对照期间相同（均约为40%）。在输注乳酸的第5小时，通过降低母体吸入氧分数诱发胎儿低氧血症，该小时内FBM仅出现8±1%（标准误）。在随后的常氧血症恢复小时内，FBM发生率仍低于对照水平。在不同日期对同一批动物进行实验，在未输注酸的情况下诱发类似的低氧血症会对FBM产生类似的抑制作用，但在随后的恢复小时内FBM发生率会恢复到对照水平。中度外周乳酸酸中毒不会减弱急性低氧血症诱发的对FBM的抑制作用，也不太可能解释长期低氧血症期间FBM发生率的恢复情况，但实际上可能介导了部分抑制作用。
