LaGamma E F, Itskovitz J, Rudolph A M
Am J Obstet Gynecol. 1982 Aug 15;143(8):933-40. doi: 10.1016/0002-9378(82)90477-x.
The effects of opiate receptor antagonism on the fetal cardiovascular response to hypoxemia were examined by means of the radionuclide-labeled microsphere technique. Heart rate, blood pressure, and cardiac output were measured during baseline periods, during hypoxemia, and before and after infusion of either naloxone (1 mg/kg) or an equivalent volume of 0.0% saline solution. Seventeen fetal sheep were subjected to maternal hypoxemia by allowing the ewes to breathe 10% oxygen (3% carbon dioxide, 87% nitrogen). The fetuses responded with bradycardia (p less than 0.002 compared with control), increased blood pressure (p less than 0.002 compared with control), and no significant change in combined ventricular output or placental blood flow. After naloxone, the bradycardia increased by 10% (p less than 0.001), and both combined ventricular output and placental blood flow fell by 20% (p less than 0.01 and p less than 0.01, respectively). The fetal bradycardic response to naloxone was reversible with atropine. In fetuses with normal oxygenation of the blood (normoxemic), naloxone had no significant effect on heart rate and blood pressure. These data indicate that endogenous opiates (e.g., endorphin and enkephalin) are important in regulating the fetal circulation during hypoxia, and that the effects of opiate receptor antagonism may be mediated through the autonomic nervous system.
采用放射性核素标记微球技术，研究了阿片受体拮抗作用对胎儿心血管系统对低氧血症反应的影响。在基线期、低氧血症期间以及注射纳洛酮（1毫克/千克）或等量0.0%盐溶液前后，测量心率、血压和心输出量。通过让母羊呼吸10%氧气（3%二氧化碳，87%氮气），使17只胎羊处于母体低氧血症状态。胎儿出现心动过缓（与对照组相比，p<0.002）、血压升高（与对照组相比，p<0.002），联合心室输出量或胎盘血流量无显著变化。注射纳洛酮后，心动过缓增加了10%（p<0.001），联合心室输出量和胎盘血流量均下降了20%（分别为p<0.01和p<0.01）。胎儿对纳洛酮的心动过缓反应可被阿托品逆转。在血液氧合正常（正常氧血症）的胎儿中，纳洛酮对心率和血压无显著影响。这些数据表明，内源性阿片类物质（如内啡肽和脑啡肽）在缺氧期间调节胎儿循环中起重要作用，阿片受体拮抗作用的影响可能通过自主神经系统介导。
