Ross M G, Sherman D, Ervin M G, Humme J, Gimpel J
Department of Obstetrics and Gynecology, Harbor-University of California, Los Angeles Medical Center, Torrance 90502.
Am J Obstet Gynecol. 1988 Dec;159(6):1407-12. doi: 10.1016/0002-9378(88)90565-0.
Amniotic fluid homeostasis is dependent on a balance of fetal fluid production and absorption. The fetal gastrointestinal tract is believed to resorb 500 to 1000 ml of amniotic fluid per day during 7 to 10 bouts of swallowing activity. However, the impact of ruminal fluid on fetal plasma composition and fluid homeostasis is largely unknown. Seven ovine fetuses (120 +/- 1 day) received intraruminal infusions of 0.9% or 3% saline solution on alternate days. In response to successive 40-minute intraruminal infusions of 0.9% saline solution (0.5 and 1.0 ml/kg/min), there was no change from basal levels of fetal plasma osmolality (295.7 +/- 2.9 mosm), plasma arginine vasopressin (1.45 +/- 0.29 pg/ml), urine osmolality (150 +/- 8 mosm), or urine volume (0.49 +/- 0.10 ml/min). In response to the 3% saline solution infusion, significant increases were noted in fetal plasma osmolality (295.4 +/- 3.1 to 302.6 +/- 2.6 mosm), plasma arginine vasopressin (1.77 +/- 0.31 to 4.84 +/- 0.79 pg/ml), and urine osmolality (157 +/- 13 to 342 +/- 25 mosm), whereas fetal urine volume significantly decreased (0.35 +/- 0.05 to 0.15 +/- 0.06 ml/min). These results indicate that hypertonic, but not isotonic, saline solution infusion into the fetal gastrointestinal tract may affect fetal plasma composition and urine production. Under conditions of significant plasma to luminal osmotic gradients, fetal gastrointestinal water and electrolyte transfer may be more rapid than can be compensated by either fetal renal function or placental equilibration.
羊水内环境稳定取决于胎儿羊水生成与吸收的平衡。据信，胎儿胃肠道在每天7至10次吞咽活动期间可重吸收500至1000毫升羊水。然而，瘤胃液对胎儿血浆成分和液体平衡的影响在很大程度上尚不清楚。七只绵羊胎儿（120±1天）每隔一天接受瘤胃内输注0.9%或3%的盐溶液。在连续40分钟瘤胃内输注0.9%盐溶液（0.5和1.0毫升/千克/分钟）后，胎儿血浆渗透压（295.7±2.9毫渗量）、血浆精氨酸加压素（1.45±0.29皮克/毫升）、尿渗透压（150±8毫渗量）或尿量（0.49±0.10毫升/分钟）的基础水平未发生变化。在输注3%盐溶液后，胎儿血浆渗透压（从295.4±3.1毫渗量升至302.6±2.6毫渗量）、血浆精氨酸加压素（从1.77±0.31皮克/毫升升至4.84±0.79皮克/毫升）和尿渗透压（从157±13毫渗量升至342±25毫渗量）显著升高，而胎儿尿量显著减少（从0.35±0.05毫升/分钟降至0.15±0.06毫升/分钟）。这些结果表明，向胎儿胃肠道输注高渗而非等渗盐溶液可能会影响胎儿血浆成分和尿液生成。在血浆与管腔存在显著渗透梯度的情况下，胎儿胃肠道水和电解质的转移可能比胎儿肾功能或胎盘平衡所能补偿的速度更快。
