Abstract
Furosemide (FU) stimulates the renin-angiotensin-aldosterone system in the newborn lamb. This study was designed to assess whether FU or acute salt loading influences the renin-angiotensin-aldosterone system in the fetus. Twelve fetal lambs 102-131 days gestational age were studied (term-145 days). FU (2 mg/kg estimated fetal weight) was infused over 1-2 min. Blood samples were drawn at 8, 20, 35 and 65 min. post infusion. In a separate study hypertonic sodium chloride (2.5 mEq/ml) was infused at a rate of 10 mEq/kg over 2 min. Blood samples were drawn at 3, 7, 15 and 30 min. post infusion. Plasma renin activity (PRA) ng/ml/hr and plasma aldosterone (Aldo) ng/dl were measured by radioimmunoassay. Baseline PRA was 3.09±.37 (M and SEM) at 100-115 days and 8.37±.91 at 120-131 days gestation (p<.01). Baseline Aldo was similar in the two groups (5.6±.03<115 and 5.6±1.3>120 days), Following FU infusion in all fetal lambs, PRA increased from a baseline of 5.37±.71 to 8.56±1.24 at 8 min. (p<.01) and 20,36±5.8 at 35 min. post infusion (p<.05). Aldo, however, did not increase. Salt loading increased plasma osmolallty from 297±1.8 to 318±5.6 mOsm/L at 3 min. post infusion (p<.001), with no change in PRA. Conclusions: between 102-131 days gestation in the lamb fetus, 1) baseline PRA increases progressively without a change in Aldo, 2) FU stimulates PRA but not Aldo, and 3) acute salt loading does not suppress PRA.
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Siegel, S., Leake, R. & Fisher, D. RESPONSE OF THE RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM TO FUROSEMIDE AND ACUTE SALT LOADING IN THE FETAL LAMB. Pediatr Res 11, 411 (1977). https://doi.org/10.1203/00006450-197704000-00252
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DOI: https://doi.org/10.1203/00006450-197704000-00252