Smith F G, Sato T, McWeeny O J, Torres L, Robillard J E
Department of Pediatrics, College of Medicine, University of Iowa, Iowa City 52242.
Am J Physiol. 1989 Dec;257(6 Pt 2):R1519-25. doi: 10.1152/ajpregu.1989.257.6.R1519.
The present study was designed to determine the influence of renal nerves in mediating the renal response to volume expansion in conscious newborn lambs. Bilateral renal denervation (n = 9) or sham surgery (n = 14) was carried out in newborn lambs 3 to 4 days before performing experiments. Lambs were between 6 and 12 days of age when studied. Chronic denervation did not alter basal neonatal renal function nor renal hemodynamics. Volume expansion with isotonic saline equal to 5% of body weight was associated with a fall in hematocrit and an increase in mean arterial blood pressure, glomerular filtration rate, urine flow rate, and Na+ excretion in intact and denervated lambs. In intact lambs, atrial natriuretic factor increased from 98 +/- 28 to 176 +/- 48 ng/ml during volume expansion and remained elevated for 1 h after volume expansion. In addition, plasma renin activity fell from 21 +/- 5 to 8 +/- 1 ng.ml-1.h-1 and aldosterone levels fell from 160 +/- 24 to 59 +/- 7 pg/ml by 150 min after the start of volume expansion. Similar changes in atrial natriuretic factor, plasma renin activity, and aldosterone were observed in denervated lambs. However, the increase in glomerular filtration rate, Na+ excretion, and fractional excretion of Na+ after volume expansion were significantly less in denervated than in intact lambs. Thus, in the newborn, the renal nerves do not appear to play a role in influencing basal renal hemodynamics and renal function but, as in the adult, the renal sympathetic nervous system does play a role in regulating fluid and electrolyte excretion during hypervolemia.
本研究旨在确定肾神经在介导清醒新生羔羊对容量扩张的肾反应中的作用。在进行实验前3至4天，对新生羔羊进行双侧肾去神经支配（n = 9）或假手术（n = 14）。研究时羔羊年龄在6至12天之间。慢性去神经支配并未改变新生儿的基础肾功能和肾血流动力学。用相当于体重5%的等渗盐水进行容量扩张，完整和去神经支配的羔羊均出现血细胞比容下降，平均动脉血压、肾小球滤过率、尿流率和钠排泄增加。在完整的羔羊中，容量扩张期间心钠素从98±28 ng/ml增加到176±48 ng/ml，并在容量扩张后1小时保持升高。此外，容量扩张开始后150分钟，血浆肾素活性从21±5 ng·ml⁻¹·h⁻¹降至8±1 ng·ml⁻¹·h⁻¹，醛固酮水平从160±24 pg/ml降至59±7 pg/ml。去神经支配的羔羊在心钠素、血浆肾素活性和醛固酮方面也有类似变化。然而，去神经支配的羔羊在容量扩张后肾小球滤过率、钠排泄和钠分数排泄的增加明显低于完整的羔羊。因此，在新生儿中，肾神经似乎在影响基础肾血流动力学和肾功能方面不起作用，但与成年人一样，肾交感神经系统在高血容量期间调节液体和电解质排泄中确实发挥作用。
