Smith F G, Sato T, McWeeny O J, Klinkefus J M, Robillard J E
Department of Pediatrics, University of Iowa, Iowa City 52242.
Am J Physiol. 1990 Nov;259(5 Pt 2):R1050-5. doi: 10.1152/ajpregu.1990.259.5.R1050.
To investigate the role of renal sympathetic nerves in the fetal response to hypervolemia, studies were carried out in conscious, chronically instrumented fetal sheep aged 137-142 days of gestation. Bilateral renal denervation (n = 9) or sham surgery (n = 8) was carried out under halothane anesthesia 3-6 days before experiments. Bilateral renal denervation did not alter basal fetal renal hemodynamics, glomerular filtration rate (GFR), or Na+ excretion. Volume expansion with 6% Dextran 70 (18 ml/kg) was associated with a fall in fetal hematocrit, a sustained increase in mean arterial blood pressure, and a sustained diuresis and natriuresis. There was no significant change in GFR during fetal hypervolemia from control levels of 4.51 +/- 0.74 ml/min (intact) and 4.43 +/- 0.43 ml/min (denervated). Atrial natriuretic factor increased from 144 +/- 34 to 464 +/- 134 pg/ml, and plasma renin activity decreased from 5.15 +/- 1.7 to 3.04 +/- 1.0 ng.ml-1.h-1 in intact animals, within 30 min of completion of the dextran infusion. Similar changes occurred in denervated fetuses. Plasma aldosterone levels remained constant in intact and denervated fetuses during hypervolemia at control levels of 40.8 +/- 5.4 and 59.3 +/- 8.4 pg/ml, respectively. These findings suggest that renal sympathetic nerves do not influence basal renal hemodynamics or function and do not appear to play an important role in the natriuretic response to volume expansion during fetal life. This can be explained by a low tonic renal nerve activity before birth.
为研究肾交感神经在胎儿对血容量过多反应中的作用，对妊娠137 - 142天的清醒、长期植入仪器的胎羊进行了研究。在实验前3 - 6天，在氟烷麻醉下进行双侧肾去神经支配（n = 9）或假手术（n = 8）。双侧肾去神经支配并未改变胎儿基础肾血流动力学、肾小球滤过率（GFR）或钠排泄。用6%右旋糖酐70（18 ml/kg）进行容量扩充与胎儿血细胞比容下降、平均动脉血压持续升高以及持续利尿和利钠有关。在胎儿血容量过多期间，GFR从完整组的4.51±0.74 ml/min和去神经组的4.43±0.43 ml/min的对照水平无显著变化。在完整动物中，在右旋糖酐输注完成后30分钟内，心房利钠因子从144±34增加到464±134 pg/ml，血浆肾素活性从5.15±1.7下降到3.04±1.0 ng·ml⁻¹·h⁻¹。去神经支配的胎儿也出现类似变化。在血容量过多期间，完整和去神经支配胎儿的血浆醛固酮水平分别维持在对照水平40.8±5.4和59.3±8.4 pg/ml不变。这些发现表明，肾交感神经不影响基础肾血流动力学或功能，并且在胎儿期对容量扩充的利钠反应中似乎不发挥重要作用。这可以通过出生前肾神经活动张力较低来解释。
