Agnew C L, Ross M G, Fujino Y, Ervin M G, Day L, Kullama L K
Perinatal Research Laboratory, Harbor-University of California Los Angeles Medical Center, Torrance 90502.
Am J Physiol. 1993 Jan;264(1 Pt 2):R197-203. doi: 10.1152/ajpregu.1993.264.1.R197.
Dehydration induces marked alterations in maternal-fetal fluid homeostasis and accompanying fetal endocrine responses. We sought to determine if the increase in fetal plasma arginine vasopressin (AVP) levels during maternal dehydration is mediated by fetal plasma hypovolemia in addition to hyperosmolality and to examine maternal and fetal plasma atrial natriuretic factor (ANF) responses to maternal dehydration and oral rehydration. Seven pregnant ewes (127 +/- 1 day) were water deprived for 72-96 h, and five of these were orally rehydrated. Dehydration induced significant increases in maternal plasma osmolality (pOSM) (300 +/- 2 to 325 +/- 8 mosmol/kg) and AVP (3.0 +/- 0.4 to 18.9 +/- 4.0 pg/ml), and decreases in plasma ANF levels (28.1 +/- 3.1 to 19.7 +/- 3.1 pg/ml). Fetal pOSM (293 +/- 3 to 314 +/- 4 mosmol/kg), AVP (2.5 +/- 0.6 to 8.1 +/- 4.8 pg/ml), and urinary fractional sodium excretion increased significantly, whereas plasma ANF and fetal blood volume did not change. After maternal water access maternal plasma AVP decreased rapidly in comparison to the gradual decrease in maternal pOSM. Fetal plasma AVP levels did not change significantly and fetal pOSM decreased more slowly than maternal pOSM. Fetal plasma ANF increased in association with increased urine flow and glomerular filtration rate after maternal rehydration. These data indicate marked differences in fetal and maternal plasma ANF and AVP responses with dehydration-induced increases in fetal plasma AVP being secondary to plasma hyperosmolality, rather than hypovolemia. Rapid suppression of maternal plasma AVP may contribute to the slower equilibration of fetal pOSM during oral, as compared with intravenous, maternal rehydration.
脱水会引起母胎液体稳态的显著改变以及相应的胎儿内分泌反应。我们试图确定母体脱水期间胎儿血浆精氨酸加压素（AVP）水平的升高是否除了高渗状态外还由胎儿血浆血容量减少介导，并研究母体和胎儿血浆心钠素（ANF）对母体脱水和口服补液的反应。七只怀孕母羊（妊娠127±1天）禁水72 - 96小时，其中五只进行口服补液。脱水导致母体血浆渗透压（pOSM）显著升高（从300±2至325±8毫摩尔/千克）和AVP升高（从3.0±0.4至18.9±4.0皮克/毫升），同时血浆ANF水平降低（从28.1±3.1至19.7±3.1皮克/毫升）。胎儿pOSM（从293±3至314±4毫摩尔/千克）、AVP（从2.5±0.6至8.1±4.8皮克/毫升）和尿钠排泄分数显著增加，而血浆ANF和胎儿血容量未发生变化。母体恢复饮水后，与母体pOSM的逐渐下降相比，母体血浆AVP迅速下降。胎儿血浆AVP水平无显著变化，且胎儿pOSM下降比母体pOSM更慢。母体补液后，胎儿血浆ANF随着尿流量和肾小球滤过率的增加而升高。这些数据表明胎儿和母体血浆ANF及AVP反应存在显著差异，脱水诱导的胎儿血浆AVP升高继发于血浆高渗状态而非血容量减少。与静脉补液相比，口服补液期间母体血浆AVP的快速抑制可能导致胎儿pOSM平衡较慢。
