Maturational changes in the fetal glomerular filtration rate

Robillard, J; Kulvinskas, Claudius; Sessions, Christine; Burmeister, Leon F.; Smith, F.

doi:10.1016/0002-9378(75)90057-5

Cited by 58 publications

(28 citation statements)

References 23 publications

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“…The presence of a close relationship between fetal G F R ml/ min and fetal body weight (Fig. l ) , as well as the absence of an increase in G F R expressed in milliliters per min per kg related to fetal body weight, concurs with previous studies done by our group (17,19) but differs from a recent acute study using fetal guinea pigs ( I 5).…”

Section: Discussionsupporting

confidence: 91%

Maturation of the Glucose Transport Process by the Fetal Kidney

et al. 1978

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Summaryperiod than later in life-suggesting that the tubular function b a s more immature than the-glome;ular function at birth (24). In order to study the maturation the glucose reabsorptive However, Brodehl (6), Baker (4), and Arant (2) were recently process by the fetal kidney, nine chronic fetal lamb Preparations able to demonstrate that the maximal glucose reabsorption per (0.66-3.72 kg) were studied and values compared to data milliliter of glomerular filtrate (Tm JGFR) was equal to or obtained from four nonpregnant ewesand urine control slightly higher than adult levels during the first weeks of life, values showed there was a close relationship between fetal thereby suggesting that glomerular tubular balance was mainglomerular filtration rate (GFR mllmin) and fetal body weight tained, (r = 0-78,P < 0.02). The fractional excretion of sodium, during It has been demonstrated during fetal life in rats (8), pigs control periods, varied from 3.86-14.76%, but no relation with (16), and lambs (1) that the fetal renal tubule reabsorbs glucose.weight Or GFR mi/min was found. The mean Alexander and Nixon (1) suggested that the fetal lamb kidney for blood glucose observed at threshold was higher in the fetus has the capacity to reabsorb most of the filtered glucose before (200 13.3 mg/lOO ml) than in ewes 2.8 mg/lOO the midpoint of gestation, confirming a previous study on the ml). Fetal glucose threshold was correlated to fetal body weight mesonephros of fetal pigs (16). They also demonstrated that (r = 0.71, P < 0.05) and fetal GFR ml/min (r = 0.74, P < phlorizin blocked glucose reabsorption (1). 0.025). r he maximum amount of glucose reabsorbed expressedThese fetal studies (1,8,16), however, were done in acute per GFR (TmJGFR) was reached in One fetus and fetal preparations in which the renal function might have been was 4.73. In fetuses, T m~ was reached since altered considerably by stress and hypoxia (1 1, 20). The present metabolic acidosis developed during the murse of glucose work was designed to study, in chronic fetal sheep preparations, infusion. ow ever, in those fetuses, the highest amount of the maturation of the glucose reabsorptive process by the fetal glucose reabsorbed expressed per unit of GFR (TdGFR), kidney during the last trimester of gestation, before glucose infusion was stopped, varied from 2.32 to 3.85 with a mean of 2.83 -c 0.26. In the adult ewes TmJGFR varied from 1.94 to 2.47, and the mean value (2.21 k 0.12) was MATERIALS AND METHODS significantly lower (P < 0.05) than the mean TmJGFR and T dNine chronic fetal lamb preparations (mixed breed Dorset GFR values found in fetuses. These data indicate that the and Suffolk) and four nonpregnant ewes were used to investigate plasma threshold values for glucose reabsorption by the fetal the renal process of glucose reabsorption. The intrauterine fetal kidney increased with fetal GFR, suggesting that (here is a weight at the time of the experiment was estimated according to parallel development in fetal tubular and glomerular function. the equa...

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Section: Discussionsupporting

confidence: 91%

Maturation of the Glucose Transport Process by the Fetal Kidney

et al. 1978

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“…It is well known that maturational changes occur in fetal renal function as term approaches. In both acute and chronic preparations it has been shown that GFR in the ovine fetus increases absolutely with increasing gestational age, but remains constant when expressed as ml/min/g of kidney wt (24)(25)(26)(27). At birth there is a disproportionate increase in GFR (25).…”

Section: Resultsmentioning

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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“…Control values were determined from fivc adult nonpregnant sheep. T h e fetuscs \vcre weighed at the end of the experiment and their age determined as previously dcscribcd (12,24). Tlic adult ewes were weighed before the experiment.…”

Section: Speculationmentioning

confidence: 99%

Influence of Fetal Extracellular Volume Contraction on Renal Reabsorption of Bicarbonate in Fetal Lambs

et al. 1977

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In orclcr to clcternline the renal thresholcl for bicarbonate in tlie fetal Ian111 ancl factors that niay influence renal reabsorption of bicarl)onate in the fetus, 18 acute fetal l a n~b preparations (110-140 clays of gestation) were stutliecl. In tlie first series of experinlents involving nine fetuses, the renal bicarbonate thresholtl of nornlal fetuses varied fro111 12.0 to 23.5 rnhl/liter with a rnenn value of 17.7 ? 1.37 n~hl/liter. This is significantly lower ( P < 0.005) than the value n~easurecl in five adult sheep of 28.7 ? 1.68 111hl/liter. There was a significant ant1 positive correlation bettveen tlie fetal pl:isn~a bicarbonate at thrcsholtl level ant1 the fetal kiclney weight, as well as fetal age. In a secontl series of experin~ents, the excretion of 1)icarl)onatc ancl socliuni was stuelied in nine fetuses I)cfore ant1 after tlehgdration by peritoneal tlialysis. After peritoneal tlialysis there was a significant clccrease in urinary p l i (ID < 0.025), 1)icarbonate excretion ( P < 0.001), socliurn excretion (P < 0.001), fractional cxcretion of socliuni (ID < 0.001), and a significant increase in bicarbonate reabsorption (P < 0.01). When glucose was replaced by ~nannitol in tlie peritoneal tlialysis floicl the effects on bicarbonate reabsorption par:~llclecl tliose rrhrn glucose bras present in tlialysis fluitl. It was also slloun that when glucose was given intravenously to the fetus, up to a plasnla concentration of 200 nig/100 1111, tllere was no effect on tlic fetal renal reabsorption of bicarbonate. These data inclicatc that the lorv tl~resholtl for bicarbonate reabsorption by tlie fetal kitlney is not clue to a lin~itecl capacity to increase 1)icarbonate or socliun~ reabsorption ancl suggest that the fetal kiclney is ablc to respontl to volu~ile clepletion by increasing its reabsorption in bicarbonate ancl electrolytes. SpeculationA nu~ilber of factors have been suggestctl to explain the low bicarbonate thresholcl observecl (luring fetal life ancl during the early newborn periocl. These inclucle the inln~aturity of the nephron, the oncotic press~lre in tlie peritubular rapillary circulation, the influence of distribution of intrarenal bloocl flow, the role playecl by the re11i11-angiotcnsir~ alclosterone sjsteni, ant1 the effect of a and / 3 aelreriergic stimulation.Tlie present study suggests that the state of high extracellular fluid volume that exists during fetal life and the early newborn period significantly influences the maturation of the renal thresl~old for bicarl)onate.Tlic regulation of acid-base homeostasis by the mature kidney involves tlic reabsorption of filtered bicarbonate on the one hand and the cxcrctiori of hydrogen ion as titrable acid and ammonium o n the other.

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Maturational changes in the fetal glomerular filtration rate

Cited by 58 publications

References 23 publications

Maturation of the Glucose Transport Process by the Fetal Kidney

Maturation of the Glucose Transport Process by the Fetal Kidney

Gestational Changes in Renal Responsiveness to Cortisol in the Ovine Fetus

Influence of Fetal Extracellular Volume Contraction on Renal Reabsorption of Bicarbonate in Fetal Lambs

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