Ross M G, Dodd A, Agnew C, Fujino Y, Ervin M G
Perinatal Research Laboratories, Harbor-UCLA Medical Center, Torrance 90502.
Biol Neonate. 1993;64(2-3):127-33. doi: 10.1159/000243982.
Ovine fetal swallowing primarily occurs in bouts of activity associated with low voltage electrocorticogram activity and breathing movements. Despite similar rates of electromyographic swallowing activity, there are significant differences in the net esophageal fluid flow among fetuses. To determine if variations in the volume of fluids accessible to the fetus (amniotic fluid, lung fluid, salivary secretions) affect fetal swallowing, we studied the effects of sublingual distilled water infusions on ovine fetal swallowing rates and esophageal flow. Seven pregnant ewes at 127 +/- 2 days gestation were chronically instrumented with maternal and fetal vascular catheters, fetal electrocortical, electro-ocular and electromyograph electrodes, an esophageal flow probe and a sublingual infusion catheter. Following a 2-hour control period, consecutive sublingual infusions of room temperature distilled water (10 and 20 ml/kg/h) were administered for 2 h each. In response to sublingual infusions, fetal plasma sodium (142.5 +/- 0.5 to 140.8 +/- 0.8 mEq/l), chloride concentrations (109.2 +/- 0.4 to 107.7 +/- 0.7 mEq/l) and osmolality (302 +/- 2 to 298 +/- 2 mOsm/kg) decreased significantly. Swallowing activity and esophageal flow did not change significantly from basal values (47 +/- 9 swallows/h, 19.2 +/- 4.2 ml/h) during the sublingual infusions. However, fetal low-voltage electrocortical activity increased significantly during both infusion periods (42 +/- 3 to 56 +/- 6%). Sublingual distilled water infusion decreases fetal plasma osmolality and alters fetal behavioral state without affecting swallowing frequency or esophageal flow.
绵羊胎儿吞咽主要发生在与低电压脑电图活动和呼吸运动相关的活动发作期间。尽管肌电图吞咽活动的速率相似，但胎儿之间的食管净液流存在显著差异。为了确定胎儿可接触到的液体量（羊水、肺液、唾液分泌）的变化是否会影响胎儿吞咽，我们研究了舌下输注蒸馏水对绵羊胎儿吞咽率和食管液流的影响。对7只妊娠127±2天的怀孕母羊进行长期监测，在母体和胎儿身上植入血管导管、胎儿脑电图、眼电图和肌电图电极、食管液流探头和舌下输注导管。在2小时的对照期后，连续进行两次舌下输注室温蒸馏水（10和20毫升/千克/小时），每次持续2小时。作为对舌下输注的反应，胎儿血浆钠浓度（从142.5±0.5降至140.8±0.8毫当量/升）、氯浓度（从109.2±0.4降至107.7±0.7毫当量/升）和渗透压（从302±2降至298±2毫渗量/千克）显著下降。在舌下输注期间，吞咽活动和食管液流与基础值（47±9次吞咽/小时，19.2±4.2毫升/小时）相比没有显著变化。然而，在两个输注期内，胎儿低电压脑电图活动均显著增加（从42±3%增至56±6%）。舌下输注蒸馏水会降低胎儿血浆渗透压并改变胎儿行为状态，但不影响吞咽频率或食管液流。
