Circulatory and humoral responses of sympathectomized fetal sheep to hypoxemia.
Circulatory and humoral responses of sympathectomized fetal sheep to hypoxemia.
复制标题
交感神经切除胎羊对低氧血症的循环和体液反应。
DOI：
10.1152/ajpheart.1983.245.5.h767
复制
发表时间：
1983
期刊：
影响因子：
--
通讯作者：
Keil,LC
中科院分区：
文献类型：
--
作者：
Iwamoto,HS;Rudolph,AM;Mirkin,BL;Keil,LC
在胎羊中，低氧血症引起动脉高压、心动过缓、血流重新分布以及血浆加压素和儿茶酚胺浓度增加。为了评估交感神经系统在介导这些反应中的作用，我们给11个长期插管胎羊6-羟基多巴胺。一些急性低氧血症的反应，实现了管理的低O2气体混合物的母羊，是相似的那些在完整的胎羊。胎儿动脉氧分压从22 +/-3（SD）Torr降至12 +/- 3（SD）Torr;胎儿心率一过性降低;通过放射性核素标记微球技术测量的合并心室输出量和脐-胎盘血流量维持不变;脑、心肌和肾上腺血流量增加，肺血流量减少。然而，在化学交感神经切除的胎儿中，动脉压或外周、肾脏和内脏循环的血流量对低氧血症的反应没有显著变化。交感神经系统在某些胎儿对低氧血症的血管反应中是重要的，但在某些关键器官的血管反应中不是必需的，因此在低氧期间对胎儿存活不是至关重要的。
In fetal sheep, hypoxemia causes arterial hypertension, bradycardia, a redistribution of blood flow, and an increase in plasma vasopressin and catecholamine concentrations. To assess the role of the sympathetic nervous system in mediating these responses, we administered 6-hydroxydopamine to 11 chronically catheterized fetal sheep. Some of the responses to acute hypoxemia, achieved by administration of a low-O2 gas mixture to the ewe, were similar to those in intact fetal sheep. Fetal arterial O2 tension decreased from 22 +/- 3 to 12 +/- 3 (SD) Torr; fetal heart rate decreased transiently; combined ventricular output and umbilical-placental blood flow, as measured by the radionuclide-labeled microsphere technique, were maintained; cerebral, myocardial, and adrenal blood flow increased, and pulmonary blood flow decreased. However, there was no significant change in arterial pressure or blood flow to the peripheral, renal, and splanchnic circulations in the chemically sympathectomized fetuses in response to hypoxemia. The sympathetic nervous system is important in certain fetal vascular responses to hypoxemia but is not necessary for vascular responses in certain critical organs and thus is not crucial for fetal survival during hypoxia.