Hargrave B Y, Iwamoto H S, Rudol A M
Cardiovascular Research Institute, University of California, San Francisco 94143.
Pediatr Res. 1989 Jul;26(1):1-5. doi: 10.1203/00006450-198907000-00001.
In the adult, atrial natriuretic peptide (ANP) has been postulated to regulate renal and cardiovascular function both when blood volume is expanded and when atrial pressure is increased. In late gestation fetal sheep, ANP has been detected in plasma concentrations higher than in pregnant adults; however, its function in the fetus is unclear. To assess the role of ANP in mediating changes in combined ventricular output and organ blood flow, GFR, urine flow rate, and urinary sodium excretion, we studied 11 chronically cannulated fetal sheep at 126 to 131 d gestation (term 145 d). We infused ANP in doses of 27 +/- 4 and 55 +/- 8 ng/kg/min into nine of the 11 fetuses and vehicle only into the remaining two fetuses. ANP increased hematocrit, Hb, and plasma protein concentrations, which suggests that blood volume decreased. Combined ventricular output and umbilical-placental blood flow, measured by the radionuclide-labeled microsphere technique, decreased from 458 +/- 158 to 344 +/- 59 ml/min/kg and 210 +/- 85 to 144 +/- 31 ml/min/kg, respectively and the calculated umbilical-placental vascular resistance increased from 0.20 +/- 0.10 to 0.32 +/- 0.09 mm Hg/ml/min/kg during the infusion of the high ANP dose. Blood flow to the gastrointestinal tract decreased with the high dose of ANP but blood flow to all other organs, mean arterial blood pressure, and heart rate did not change significantly. The effects of ANP on fetal renal function were minimal. Thus, ANP may play a role in maintaining fluid homeostasis in the fetus through its ability to decrease blood volume and to decrease combined ventricular output and umbilical-placental blood flow.
在成年人中，心房利钠肽（ANP）被认为在血容量增加和心房压力升高时均可调节肾脏和心血管功能。在妊娠晚期的胎羊中，已检测到其血浆浓度高于怀孕的成年人；然而，其在胎儿中的功能尚不清楚。为了评估ANP在介导联合心室输出量、器官血流量、肾小球滤过率（GFR）、尿流率和尿钠排泄变化中的作用，我们研究了11只在妊娠126至131天（足月为145天）长期插管的胎羊。我们将剂量为27±4和55±8 ng/kg/min的ANP注入11只胎儿中的9只，仅将溶剂注入其余2只胎儿。ANP使血细胞比容、血红蛋白和血浆蛋白浓度升高，这表明血容量减少。通过放射性核素标记微球技术测量，联合心室输出量和脐-胎盘血流量分别从458±158降至344±59 ml/min/kg和从210±85降至144±31 ml/min/kg，并且在注入高剂量ANP期间，计算得出的脐-胎盘血管阻力从0.20±0.10升至0.32±0.09 mmHg/ml/min/kg。高剂量ANP使胃肠道血流量减少，但所有其他器官的血流量、平均动脉血压和心率均无显著变化。ANP对胎儿肾功能的影响极小。因此，ANP可能通过其降低血容量以及降低联合心室输出量和脐-胎盘血流量的能力，在维持胎儿体内液体平衡中发挥作用。
