Bassett J M, Burks A H, Levine D H, Pinches R A, Visser G H
Obstet Gynecol. 1985 Dec;66(6):755-61.
To investigate metabolic and endocrine changes in the fetus during prolonged maternal tocolysis with beta sympathomimetic drugs, ritodrine hydrochloride (2.1 micrograms/kg per minute) was infused into pregnant sheep near term. Confirming earlier studies, maternal plasma metabolite and hormone levels changed greatly during the first six to eight hours of infusion. Changes in the fetus paralleled these closely: glucose, lactate, and insulin increased sharply, but glucagon and alpha-amino acid nitrogen decreased. After this, most maternal and fetal plasma metabolite and hormone levels returned to the normal range and were unchanged by infusion for 72 to 96 hours. Fetal lactate levels, however, remained elevated. Similar changes occurred during interrupted maternal infusions of ritodrine. Prolonged infusion of ritodrine leads to diminished responsiveness in beta-adrenergic mechanisms regulating maternal plasma metabolite and hormone levels. Comparable unresponsiveness of fetal beta-adrenergic mechanisms, though less certain, could increase hazards during delivery and adaptation to postnatal life.
为了研究在使用β-拟交感神经药物进行长时间母体保胎治疗期间胎儿的代谢和内分泌变化，将盐酸利托君（每分钟2.1微克/千克）输注到接近足月的怀孕绵羊体内。正如早期研究证实的那样，在输注的前六至八小时内，母体血浆代谢物和激素水平发生了很大变化。胎儿的变化与这些变化密切平行：葡萄糖、乳酸和胰岛素急剧增加，但胰高血糖素和α-氨基酸氮减少。在此之后，大多数母体和胎儿血浆代谢物和激素水平恢复到正常范围，并且在输注72至96小时后没有变化。然而，胎儿乳酸水平仍然升高。在中断母体输注利托君期间也发生了类似的变化。长时间输注利托君会导致调节母体血浆代谢物和激素水平的β-肾上腺素能机制反应性降低。胎儿β-肾上腺素能机制的类似无反应性虽然不太确定，但可能会增加分娩期间和适应产后生活的风险。
