Action of Atrial Natriuretic Peptide in the Immature Ovine Kidney

Shine, Peter; McDougall, John G.; Towstoless, M; Wintour, E. M.

doi:10.1203/00006450-198707000-00003

Cited by 36 publications

(13 citation statements)

References 11 publications

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“…There is evidence that ANP increases urine flow (32,33) and/or sodium excretion and fractional excretion of sodium (8). Taken together these data indicate that exogenous ANP probably increases sodium and water excretion in the normal euvolemic fetus.…”

Section: Role Of Anp In Maintenance Of Fetal Sodium and Water Excretionsupporting

confidence: 53%

Role of Endogenous Atrial Natriuretic Peptide in Chronic Anemia in the Ovine Fetus: Effects of a Non-Peptide Antagonist for Atrial Natriuretic Peptide Receptor

Silberbach

et al. 1995

Pediatr Res

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ARSChronic fetal anemia causes polyhydramnios and fetal hydrops and is associated with increased fetal diuresis and natriuresis. To determine the role of atrial natriuretic peptide (ANP) in the renal adaptation to chronic fetal anemia we studied the effects of HS-142-1 (HS), a specific inhibiIor of the guanylate cyclase-linked ANP receptor (ANP -GC), in two groups of chronically instrume nted unanesthetized sheep fetuses. Seven fetuses were made anemic by serial isovolemic hemorrhage over 1 wk, and five fetuses served as nonanemic controls. Over the 7 d of hemorrhage ANP concentrations increased (45 ± 7 to 234 ± 15 fmol/mL). Hematocrit and arterial blood oxygen content were significantly lower in the anemic compared with the nonanemic fetuses (13.8 ± 0.7 versus 34.6 ± 2.3% and 0.7 ± 0.1 versus 2.6 ± 0.2 mrnol/L). Before HS urine flow rate, urinary sodium excretion, fractional excretion of sodium, and renal blood flow we re increased in the anemic fetuses, and the extracellular fluid volume (inulin space) was increased (674 ± 94 versus 497 ± 71 mL/kg). However, GFR was not different between the groups. HS caused a significant increase in the central venous pressure of the anemic fetuses (0.49 ± 0.03 to 0.70 ± 0.05 kPa). Urinary excretion of cGMP was considered to be a marker of endogenous ANP renal effect and was measured before and after a single bolus of HS (5.2 ± 0.30 mg/kg). HS decreased urinary cGMP excretion to 50 and 37% of baseline levels in anemic and nonanemic fetuses, respectively. Urine flow decreased in both nonanemic and anemic fetuses (0.48 ± 0.13 to 0.25 ± 0.06 and 1.30 ± 0.66 ± 0.06 ml.zmin). Sodium excretion decreased in both groups after HS (19 ± 5 to 9 ± 2 and 83 ± 16 to 39 ± 5 p,mol/min). GFR decreased after HS (3.0 ± 0.8 to 2.4 :!:: 0.5 and Alterati ons in feta l kidney function may play an important role in stabilizing the fetus stressed by prolonged anemia. In

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Section: Role Of Anp In Maintenance Of Fetal Sodium and Water Excretionsupporting

confidence: 53%

Role of Endogenous Atrial Natriuretic Peptide in Chronic Anemia in the Ovine Fetus: Effects of a Non-Peptide Antagonist for Atrial Natriuretic Peptide Receptor

Silberbach

et al. 1995

Pediatr Res

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“…Recently it has been demonstrated (17) in this laboratory that infusions of ANF (4.4 pg/h) into relatively immature ovine fetuses reduce FRN, and FRL; from 96.5 + 1.0 and 64.3 k 7.5% to 86.5 a 2.8 and 46.8 + 9.6%. In the present study similar reductions in FRN, and FRL, were seen from 96.6 2 0.2 and 65.7 a 2.2% to 87.35 t-3.0 and 47.0 f 7.4%.…”

Section: Resultsmentioning

confidence: 99%

“…Lithium was measured in plasma and urine using a Varian Spectra AA-40 atomic absorption spectrophotometer (Varian Associates, Inc., Palo Alto, CA). This procedure has been described previously by Shine et al (17).…”

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confidence: 99%

Gestational Changes in Renal Responsiveness to Cortisol in the Ovine Fetus

1989

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ABSTRACT. The ontogenetic renal responsiveness to exogenous cortisol was examined in the chronically cannulated ovine fetus. The contribution of effects a t proximal and distal tubule of the kidney were studied also. Cortisol (81.5 pg/h) was infused into immature ovine fetuses (mean gestational age -113.9 days) on five occasions and increased blood cortisol from 0.8 f 0.5 to 21.3 + 6.2 nmol/ liter. This dose of cortisol produced a highly significant diuresis and natriuresis, in part due to an increase in GFR and in part due to a significant decrease in proximal tubular reabsorption of sodium. Cortisol (107.2 + 4.7 &h) was infused into mature fetuses (mean gestational age 133.4 days) and produced an increase in blood cortisol concentration from 11.4 + 5.6 to 33.7 2 6.8 nmol/liter. No natriuresis or diuresis was seen in the mature fetuses. Cortisol caused a significant depression of proximal tubular sodium reabsorption in mature fetuses, but this extra load was reabsorbed in the distal tubule in these fetuses. The inability of the premature or very low birth wt baby to maintain normal sodium balance on a standard salt intake may be due, at least in part, to a "fetal" renal response to the high plasma cortisol concentrations found in such babies. As the kidney matures it becomes capable of increasing distal tubular sodium reabsorption to compensate for any increased distal tubular fluid delivery. (Pediatr Res 26: 6-10, 1989) Abbreviations FRN,, fractional reabsorption of sodium FR,,i, fractional reabsorption of lithium uN,,v, uKV, UclV, Uc.V, renal excretion rate of sodium/ potassium/chloride/calcium may be responsible for neonatal hyponatremia. However, subsequent investigations have shown that a characteristic of this defect is decreased proximal tubule reabsorption of sodium (2) implying that renal insensitivity to aldosterone may be only partially responsible. The relative immaturity of renal function in very low birth wt and premature neonates seems to be important in the pathogenesis of hyponatremia. Premature neonates exhibit a greater natriuresis and a lower GFR in response to oral salt loading when compared to full-term neonates (5, 6). This is consistent with histopathologic studies that show that glomerular formation in the human infant is not complete until late in gestation (7), whereas tubular development is not complete until 1 y after birth (8).In mature mammals the presence of adrenal steroids is essential for normal renal function. A characteristic of adrenalectomized or hypophysectomized animals and patients with adrenal or pituitary insufficiency is a delayed diuresis following oral or parenteral water loading, accompanied by impaired sodium conservation and reduced GFR and renal blood flow. Administration of deoxycortisone acetate or aldosterone in the presence of normal sodium balance and extra-cellular volume has no effect on the delayed diuresis, whereas cortisol-like steroids correct this diuresis (9-1 1).Clinical investigations have reported that premature neonates have higher plasma co...

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“…Basal arterial plasma ANP concentrations are greater in the fetus than in the pregnant adult and increase further after volume expansion and acute hypoxemia (10,11). Increases in plasma ANP concentrations within a physiologic range decrease combined ventricular output and umbilical-placental blood flow (12), but do not significantly alter mean arterial blood pressure or heart rate (12,13). At present, relatively little is known about the effects of ANP on the fetal pulmonary vasculature.…”

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confidence: 99%

Pulmonary Vascular Effects of Exogenous Atrial Natriuretic Peptide in Sheep Fetuses

et al. 1990

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ABSTRACT. In the adult, atrial natriuretic peptide (ANP) regulates renal and cardiovascular function when blood volume is expanded, when atrial pressure is increased, and when arterial oxygen content is decreased. In late gestation fetal sheep, plasma ANP concentrations are higher than in pregnant adults; however, ANP function in the fetus is unclear. To assess the possible role of ANP in mediating changes in pulmonary blood flow, we studied six chronically cannulated fetal sheep at 132-134 d gestation (term 145 d). We infused ANP in doses of 4.0 + 0.48, 16.0 f

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Action of Atrial Natriuretic Peptide in the Immature Ovine Kidney

Cited by 36 publications

References 11 publications

Role of Endogenous Atrial Natriuretic Peptide in Chronic Anemia in the Ovine Fetus: Effects of a Non-Peptide Antagonist for Atrial Natriuretic Peptide Receptor

Role of Endogenous Atrial Natriuretic Peptide in Chronic Anemia in the Ovine Fetus: Effects of a Non-Peptide Antagonist for Atrial Natriuretic Peptide Receptor

Gestational Changes in Renal Responsiveness to Cortisol in the Ovine Fetus

Pulmonary Vascular Effects of Exogenous Atrial Natriuretic Peptide in Sheep Fetuses

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