Cheung C Y
Department of Reproductive Medicine, University of California, San Diego, La Jolla 92093.
Am J Physiol. 1994 Aug;267(2 Pt 2):R380-6. doi: 10.1152/ajpregu.1994.267.2.R380.
Endothelin is a potent vasoconstrictor synthesized by vascular endothelial cells. In the adult, endothelin has been shown to stimulate the release of atrial natriuretic factor (ANF) through a direct action on atrial cardiocytes. The present study was designed to investigate, in the fetus, whether endothelin would similarly release ANF into the circulation. In addition, the effects of endothelin on fetal cardiovascular and urinary functions were explored. Chronically catheterized ovine fetuses between 126 and 139 days gestation (term 147 days) were used for the study. After a 30-min control period, the fetuses were infused intravenously with vehicle (n = 6) or endothelin-1 (n = 9) at 25 ng.min-1.kg-1 for 30 min, and this was followed by a 60-min recovery period. In response to endothelin infusion, plasma ANF levels were significantly elevated. Endothelin infusion acutely increased fetal arterial pressure without affecting venous pressure. Fetal heart rate decreased, and blood volume was reduced. Fetal urine flow rate and urinary excretion of electrolytes did not change during the endothelin infusion but were elevated during the recovery period. The fetus developed hypoxia and acidemia. Thus our study demonstrates that endothelin is effective in stimulating ANF release in the fetus, and this effect appears to be unrelated to the venous pressure changes. In addition, the results suggest that endothelin is a potent vasoconstrictor of the fetal systemic and umbilical vascular beds. The decrease in blood volume and increase in urinary excretion of fluid and electrolytes in response to endothelin are consistent with the known actions of ANF, which is elevated during endothelin infusion.
内皮素是一种由血管内皮细胞合成的强效血管收缩剂。在成年人中，内皮素已被证明可通过直接作用于心房心肌细胞来刺激心房利钠因子（ANF）的释放。本研究旨在调查在胎儿体内，内皮素是否会同样将ANF释放到循环中。此外，还探讨了内皮素对胎儿心血管和泌尿功能的影响。本研究使用了妊娠126至139天（足月为147天）的慢性插管绵羊胎儿。在30分钟的对照期后，将胎儿静脉注射载体（n = 6）或内皮素-1（n = 9），剂量为25 ng·min⁻¹·kg⁻¹，持续30分钟，随后是60分钟的恢复期。作为对内皮素输注的反应，血浆ANF水平显著升高。内皮素输注急性增加了胎儿动脉压，而不影响静脉压。胎儿心率下降，血容量减少。在输注内皮素期间，胎儿尿流率和电解质尿排泄没有变化，但在恢复期升高。胎儿出现了缺氧和酸血症。因此，我们的研究表明，内皮素在刺激胎儿体内ANF释放方面是有效的，并且这种作用似乎与静脉压变化无关。此外，结果表明内皮素是胎儿全身和脐血管床的强效血管收缩剂。内皮素引起的血容量减少以及液体和电解质尿排泄增加与ANF的已知作用一致，ANF在输注内皮素期间升高。
