Siegel S R
Circ Res. 1981 Jan;48(1):34-8. doi: 10.1161/01.res.48.1.34.
The effects of two doses of angiotensin II (0.025 micrograms/kg per min and 0.25 micrograms/kg per min) on plasma renin activity (PRA), aldosterone concentration, creatinine clearance, and sodium and potassium excretion were studied in two groups of 2- to 3-week-old lambs. The 0.025 micrograms/kg per min dose of angiotensin II also was studied in six adult ewes. In response to the angiotensin II infusions, PRA decreased in the newborns from baselines of 24.5 +/- 2.3 ng/ml per hr (mean +/- SE) and 22.9 +/- 3.5 to 13.6 +/- 0.8 and 13.0 +/- 2.2 at 30 minutes (P < 0.01), respectively, and returned to baseline at 60 minutes; PRA decreased from 1.7 +/- 0.1 to 0.95 +/- 0.3 ng/ml per hr at 30 minutes (P < 0.01) in the ewe and returned to baseline at 60 minutes. Plasma aldosterone increased in the newborns from baselines of 17.4 +/- 5.0 ng/dl and 14.7 +/0 3.9 to 33.1 +/- 6.9 and 32.5 +/- 6.3, respectively, at 15 minutes (P < 0.01) and returned to baseline at 60 minutes. Plasma aldosterone increased from 4.3 +/- 0.7 to 9.2 +/- 2.0 ng/dl in the ewe, and returned to baseline at 60 minutes. The change in the PRA and aldosterone responses from baseline to peak for the low and high angiotensin dose was similar in the newborn lambs and greater than in the ewe (P < 0.01). There was no change in the creatinine clearance, plasma sodium, or hematocrit. Urine sodium excretion increased from 0.16 +/- 0.04 total mEq/30 min to 0.87 +/- 0.27 (P < 0.05) in the newborns during the 0.25 micrograms/kg per min angiotensin II infusion. We conclude that, under basal conditions, the newborn lamb has high PRA and aldosterone levels with decreased pressor and increased aldosterone and renin release responsiveness to angiotensin II compared to the adult.
在两组2至3周龄的羔羊中，研究了两种剂量的血管紧张素II（0.025微克/千克每分钟和0.25微克/千克每分钟）对血浆肾素活性（PRA）、醛固酮浓度、肌酐清除率以及钠和钾排泄的影响。还在6只成年母羊中研究了0.025微克/千克每分钟剂量的血管紧张素II。在输注血管紧张素II后，新生羔羊的PRA从基线水平每小时24.5±2.3纳克/毫升（平均值±标准误）和22.9±3.5分别降至30分钟时的13.6±0.8和13.0±2.2（P<0.01），并在60分钟时恢复到基线水平；成年母羊的PRA从每小时1.7±0.1降至30分钟时的0.95±0.3纳克/毫升（P<0.01），并在60分钟时恢复到基线水平。新生羔羊的血浆醛固酮从基线水平17.4±5.0纳克/分升和14.7±3.9分别在15分钟时升至33.1±6.9和32.5±6.3（P<0.01），并在60分钟时恢复到基线水平。成年母羊的血浆醛固酮从4.3±0.7升至9.2±2.0纳克/分升，并在60分钟时恢复到基线水平。新生羔羊中低剂量和高剂量血管紧张素从基线到峰值的PRA和醛固酮反应变化相似，且大于成年母羊（P<0.01）。肌酐清除率、血浆钠或血细胞比容没有变化。在输注0.25微克/千克每分钟血管紧张素II期间，新生羔羊的尿钠排泄从每30分钟0.16±0.04总毫当量增加到0.87±0.27（P<0.05）。我们得出结论，在基础条件下，新生羔羊的PRA和醛固酮水平较高，与成年羊相比，其对血管紧张素II的升压反应降低，醛固酮和肾素释放反应性增加。
