Rawashdeh N M, Ray N D, Sundberg D K, Rose J C
Department of Physiology, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27103.
Am J Physiol. 1988 Jul;255(1 Pt 2):R67-72. doi: 10.1152/ajpregu.1988.255.1.R67.
We studied norepinephrine (NE) and plasma renin activity (PRA) responses to sodium nitroprusside (NP)-induced hypotension in seven chronically catheterized fetal lambs 0.79-0.94 gestation (mature) and in seven fetuses 0.64-0.72 gestation (immature) 4 or 5 days after surgery. We infused intravenously 5% dextrose in water (DW) or NP in DW to reduce arterial pressure 30% in fetuses for 10 min. Initial infusion choice was random, and the two infusions were separated by 24-48 h. In both groups, basal NE levels were similar and doubled in response to hypotension. In mature fetuses, PRA basal levels were 6.89 +/- 1.80 ng.ml-1.h-1 and increased two- to threefold with hypotension. In immature fetuses, PRA basal levels were 2.42 +/- 0.86 ng.ml-1.h-1 and did not change with hypotension. No changes were observed with DW infusion in either group. Arterial blood gases were normal and remained unchanged. We conclude that in the lamb fetus, NE responses to hypotension are present before and are independent of the development of PRA responses and that before 0.72 gestation there is a functional deficit in the renin-angiotensin system.
我们研究了7只妊娠0.79 - 0.94（足月）且术后4或5天长期插管的胎羊以及7只妊娠0.64 - 0.72（未足月）的胎羊对硝普钠（NP）诱导的低血压时去甲肾上腺素（NE）和血浆肾素活性（PRA）的反应。我们通过静脉输注5%葡萄糖水溶液（DW）或DW中的NP，使胎儿动脉压降低30%并持续10分钟。初始输注选择是随机的，两次输注间隔24 - 48小时。在两组中，基础NE水平相似，且对低血压反应时增加一倍。在足月胎儿中，PRA基础水平为6.89±1.80 ng·ml⁻¹·h⁻¹，低血压时增加两到三倍。在未足月胎儿中，PRA基础水平为2.42±0.86 ng·ml⁻¹·h⁻¹，低血压时无变化。两组输注DW均未观察到变化。动脉血气正常且保持不变。我们得出结论，在胎羊中，NE对低血压的反应在PRA反应出现之前就已存在且与之无关，并且在妊娠0.72之前肾素 - 血管紧张素系统存在功能缺陷。
