Maternal dehydration-rehydration: fetal plasma and urinary responses

1988 ◽  
Vol 255 (5) ◽  
pp. E674-E679 ◽  
Author(s):  
M. G. Ross ◽  
D. J. Sherman ◽  
M. G. Ervin ◽  
R. Castro ◽  
J. Humme
Keyword(s):  
Glomerular Filtration Rate ◽  
Arginine Vasopressin ◽  
Filtration Rate ◽  
Urine Volume ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Fetal Plasma ◽  
Urine Production ◽  
The Impact ◽  
Observation Period

Pregnant women may be exposed to exercise, thermal, or gastrointestinal (hyperemesis) water loss, all of which commonly induce a greater than 10 mosmol increase in plasma osmolality. Although fetal osmolality is dependent on maternal osmolality, the impact of maternal dehydration and subsequent maternal rehydration on the fetus has not been explored. Five pregnant ewes with singleton fetuses (136 +/- 1 day) were water deprived for 36 h resulting in a significant increase in plasma osmolality (298 +/- 3.4 to 313 +/- 5.0 mosmol). In response to maternal dehydration, fetal plasma osmolality (297.0 +/- 4.1 to 309.3 +/- 4.1 mosmol), arginine vasopressin (AVP) levels (1.5 +/- 0.2 to 7.9 +/- 1.0 pg/ml), hematocrit (35.1 to 38.6%), and urine osmolality (161.3 +/- 10.7 to 348.9 +/- 21.9 mosmol) significantly increased. Subsequently, ewes were rehydrated over 4 h with intravenously infused 0.45% saline (20 ml.kg-1.h-1). In response to maternal rehydration, maternal and fetal plasma osmolality decreased to basal values (298.9 +/- 3.2 and 300.1 +/- 3.8 mosmol, respectively) and fetal glomerular filtration rate (1.72 +/- 0.30 to 3.08 +/- 0.66 ml/min) and urine volume significantly increased (0.33 +/- 0.02 to 0.71 +/- 0.13 ml/min). However, fetal hematocrit (37.4%), plasma AVP (3.1 +/- 0.9 pg/ml), and urine osmolality (255.4 +/- 28.8 mosmol) did not return to basal levels during the observation period. These results demonstrate fetal hyperosmolality, blood volume contraction, AVP secretion, and altered urine production in response to maternal dehydration. Despite maternal rehydration and normalization of maternal and fetal plasma osmolality, fetal endocrine and fluid responses are prolonged.(ABSTRACT TRUNCATED AT 250 WORDS)

Intraruminal rehydration of ovine fetuses

1991 ◽  
Vol 261 (6) ◽  
pp. R1381-R1387
Author(s):  
M. G. Ross ◽  
D. J. Sherman ◽  
M. G. Ervin ◽  
L. Day
Keyword(s):  
Blood Pressure ◽  
Glomerular Filtration Rate ◽  
Filtration Rate ◽  
Plasma Osmolality ◽  
Urine Osmolality ◽  
Distilled Water ◽  
Intravascular Volume ◽  
Fetal Plasma ◽  
Arterial Blood ◽  
Arterial Po2

During oral rehydration of adult mammals, oropharyngeal stimulation, the act of swallowing, and/or gastric factors contribute to a rapid decrease in plasma arginine vasopressin (AVP) that precedes plasma osmolality changes. To determine whether similar mechanisms are present in the developing fetus, six chronically prepared ovine fetuses were rehydrated with intraruminal (IR) distilled water infusions (1 ml.kg-1.min-1 for 60 min) after 43 +/- 3 h of maternal water deprivation. In response to maternal dehydration, significant increases were noted in maternal and fetal mean plasma osmolalities, sodium and AVP concentrations, and fetal urine osmolality. As estimated by hematocrit, fetal intravascular volume decreased by 11%. Fetal rehydration via IR distilled water infusion evoked a significant decrease in fetal plasma osmolality but no change in urine osmolality. Unexpectedly, fetal arterial blood pressure increased and arterial PO2 decreased while fetal hematocrit indicated a further 7% decrease in intravascular volume after the IR infusion. There was a nonsignificant trend toward increased fetal glomerular filtration rate, urine volume, and plasma AVP concentrations. Identical IR water infusions to five euhydrated fetuses resulted in significant decreases in fetal plasma osmolality and increases in glomerular filtration rate, urine flow, and osmolar excretion. The euhydrated fetuses also exhibited significant increases in mean arterial blood pressure and hematocrit and decreased fetal arterial PO2. These results indicate that IR water does not suppress AVP secretion in the dehydrated ovine fetus. Rather, both euhydrated and dehydrated fetuses exhibit an idiosyncratic vasoconstrictive response to IR water.

Fetal recirculation of amniotic fluid arginine vasopressin

1986 ◽  
Vol 250 (3) ◽  
pp. E253-E258
Author(s):  
M. G. Ervin ◽  
M. G. Ross ◽  
R. D. Leake ◽  
D. A. Fisher
Keyword(s):  
Amniotic Fluid ◽  
Arginine Vasopressin ◽  
Urine Volume ◽  
Fetal Lung ◽  
Biologically Active ◽  
Base Line ◽  
Lung Fluid ◽  
Fetal Plasma ◽  
Urine Production ◽  
Fetal Urine

Amniotic fluid volume reflects a balance between fetal lung fluid and fetal urine production and fluid reabsorption via fetal swallowing. Arginine vasopressin (AVP) infusion decreases both fetal lung fluid and urine production and increases amniotic fluid osmolality and AVP concentration. In the present study we assessed the effect of amniotic fluid AVP injection on plasma AVP (n = 6) and renal function (n = 4) in chronically catheterized fetal lambs (X gestation = 130 days). Thirty minutes after addition of 25 micrograms of synthetic AVP into the amniotic cavity, mean +/- SE fetal plasma AVP increased from a base line of 2.7 +/- 0.2 to 14.6 +/- 3.4 pg/ml (P less than 0.01). One hundred and twenty minutes after injection, plasma AVP had increased to 26.9 +/- 5.7 pg/ml. Fetal urine volume did not change (0.78 +/- 0.01 ml/min) but significant increases in urine osmolality (169 +/- 19 to 315 +/- 25 mosm) and urine sodium (64 +/- 11 to 125 +/- 11 mueq/ml) were observed 120 min after AVP administration. In conclusion, amniotic fluid AVP levels can affect fetal plasma AVP concentration, and AVP absorbed from the amniotic fluid by the fetus remains biologically active.

Cisplatin nephrotoxicity in rats: defect in papillary hypertonicity

1981 ◽  
Vol 241 (2) ◽  
pp. F175-F185 ◽  
Author(s):  
R. Safirstein ◽  
P. Miller ◽  
S. Dikman ◽  
N. Lyman ◽  
C. Shapiro
Keyword(s):  
Glomerular Filtration Rate ◽  
Proximal Tubule ◽  
Glomerular Filtration ◽  
Filtration Rate ◽  
Collecting Duct ◽  
Urine Volume ◽  
Distal Tubule ◽  
Urine Osmolality ◽  
Solute Content ◽  
Cisplatin Nephrotoxicity

We examined the effects of cisplatin (5 mg/kg BW) on renal function in rats. Three days after administration of cisplatin whole kidney clearance of inulin fell and 24-h urine volume increased. Maximal urine osmolality and papillary solute content were reduced. Superficial nephron glomerular filtration rate measured along the proximal tubule, where no leak of inulin could be demonstrated, was reduced in cisplatin-treated animals. Differences between superficial nephron glomerular filtration rate determined in proximal and distal tubules were greater in cisplatin-treated rats than in control rats. Neither a change in fluid or sodium movement along superficial nephrons nor a reduced early distal tubule transepithelial sodium gradient explain the polyuria. Urea was reabsorbed from, not added to, the loop fluid in cisplatin-treated animals. Morphologic changes were evident in the S3 segment of the proximal tubule in cisplatin-treated animals but the glomeruli were normal. Polyuria occurred despite diminished glomerular filtration rate in cisplatin nephrotoxicity. The diminished concentration of salt and urea in the papilla as a result of abnormal function of the collecting duct or pars recta portion of the proximal tubule contributed to the defect in concentrating ability.

Continuous ovine fetal hemorrhage: sensitivity of plasma and urine arginine vasopressin response

1986 ◽  
Vol 251 (4) ◽  
pp. E464-E469 ◽  
Author(s):  
M. G. Ross ◽  
M. G. Ervin ◽  
R. D. Leake ◽  
J. A. Humme ◽  
D. A. Fisher
Keyword(s):  
Blood Volume ◽  
Arginine Vasopressin ◽  
Urine Volume ◽  
Urine Osmolality ◽  
Fetal Plasma ◽  
Equivalent Rate ◽  
Fetal Urine ◽  
Ovine Fetus ◽  
Ovine Fetal ◽  
Fetal Response

Intravascular hemorrhage of the ovine fetus is a potent stimulus for arginine vasopressin (AVP) secretion. However, the method (acute, continuous) and rate of blood withdrawal may influence the fetal response. To determine the hemorrhage threshold for AVP secretion in response to slow continuous hemorrhage, five chronically catheterized ovine fetuses were continuously hemorrhaged (0.6% blood vol/min) to 24-30% blood volume withdrawal. Immediately after hemorrhage fetal blood was reinfused at an equivalent rate. In addition to AVP measurements by radioimmunoassay, fetal urinary responses were monitored as an index of fetal AVP secretion. Significant increases in plasma AVP occurred during hemorrhage (1.0 +/- 0.1 to 8.0 +/- 2.0 pg/ml). The fetal plasma AVP-hemorrhage threshold, as defined by regression analysis, occurred at withdrawal of 13.0% blood volume. Fetal urine volume significantly decreased from a mean basal rate of 0.59 +/- 0.03 to 0.21 +/- 0.06 ml/min at the completion of hemorrhage. Urinary sodium, potassium, and osmolar excretion also significantly decreased at the completion of hemorrhage. Urinary AVP excretion, urine osmolality, sodium, and potassium concentrations did not change significantly during the hemorrhage period but increased significantly during the reinfusion period; the delay a result of renal and catheter dead space. Reinfusion of blood resulted in a return of plasma AVP to basal levels. These results define a threshold for AVP secretion and demonstrate significant urinary effects in response to slow continuous hemorrhage.

Endocrine and fluid-balance responses to amniotic and allantoic fluid loss in sheep

1990 ◽  
Vol 259 (4) ◽  
pp. R745-R752 ◽  
Author(s):  
K. A. Dickson ◽  
S. B. Hooper ◽  
I. C. McMillen ◽  
R. Harding
Keyword(s):  
Amniotic Fluid ◽  
Fluid Balance ◽  
Arginine Vasopressin ◽  
Plasma Concentrations ◽  
Plasma Osmolality ◽  
Allantoic Fluid ◽  
Maternal Plasma ◽  
Fetal Plasma ◽  
Arterial Blood ◽  
Urine Production

Our aim was to determine fetal and maternal endocrine and fluid-balance responses to prolonged loss of amniotic and allantoic fluids in sheep. In seven sheep, amniotic and allantoic fluids were drained [379.1 +/- 20.1 (SE) ml/day] from 107 to 135.3 +/- 0.6 days of gestation (term: 145 days). The results from these sheep were compared with those from seven control sheep. Maternal water intake, urine production, and urine osmolality were not altered by fluid drainage, nor were fetal and maternal arterial blood gases, pH, or plasma osmolalities. Fluid drainage increased amniotic, but not allantoic, fluid osmolality. Maternal plasma cortisol concentration increased with fluid drainage, but maternal plasma concentrations of prolactin and arginine vasopressin were unchanged. Fluid drainage increased prolactin concentrations in fetal plasma and amniotic fluid, but fetal plasma concentrations of cortisol (hydrocortisone), arginine vasopressin, norepinephrine, and epinephrine were unchanged. Our results show that the fetus is capable of maintaining its plasma osmolality despite prolonged loss of fluid from its amniotic and allantoic sacs and that this is associated with alterations in the production rate and the composition of amniotic fluid.

Changes in glomerular filtration rate, lithium clearance and plasma protein clearances in the early phase after unilateral nephrectomy in living healthy renal transplant donors

1988 ◽  
Vol 75 (6) ◽  
pp. 655-659 ◽  
Author(s):  
S. Strandgaard ◽  
A. Kamper ◽  
P. Skaarup ◽  
N. H. Holstein-Rathlou ◽  
P. P. Leyssac ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Plasma Protein ◽  
Immunoglobulin G ◽  
Filtration Rate ◽  
Early Response ◽  
Unilateral Nephrectomy ◽  
Lithium Clearance ◽  
Β2 Microglobulin ◽  
Observation Period

1. Glomerular and tubular function was studied before and 2 months after unilateral nephrectomy in 14 healthy kidney donors by measurement of the clearances of 51Cr-labelled ethylenediaminetetra-acetate, lithium, β2-microglobulin, albumin and immunoglobulin G. 2. The glomerular filtration rate (GFR) of the kidney that remained in the donor rose from 45 ± 10 (mean ± sd) to 59 ± 10 ml/min (P < 0.01) 5 days after contralateral nephrectomy and remained at this level through the observation period. 3. The lithium clearance (CLi) of the remaining kidney rose from 11.6 ± 3.7 to 20.5 ± 8.2 ml/min (P < 0.01) and remained significantly elevated throughout the observation period. 4. Absolute proximal fluid reabsorption rate (APR), which was estimated as GFR minus CLi, was unchanged 5 days after contralateral nephrectomy, but then rose gradually to reach significantly elevated levels after 4 weeks. 5. Fractional proximal reabsorption (FPR; APR/GFR) fell from 0.75 ± 0.06 to 0.66 ± 0.11 (P < 0.01) but subsequently rose to levels not significantly decreased from normal. 6. Twenty-four hour fractional clearances of β2-microglobulin, albumin and immunoglobulin G rose markedly on the day of nephrectomy, peaked at 2–3 days and subsequently fell to moderately elevated levels. 7. Both the CLj and the plasma protein clearance studies demonstrate that the early response of the remaining kidney to contralateral nephrectomy in man is an increase in GFR, an unchanged APR and a fall in FPR. The proximal tubules thus initially handle the increased filtrate load by passing it on to more distal nephron segments. Within 2–4 weeks, an adaptive increase is seen in proximal reabsorption of both protein and fluid, resulting in an almost complete normalization of glomerulotubular balance.

scholarly journals The Impact of Interlaboratory Differences in Cystatin C Assay Measurement on Glomerular Filtration Rate Estimation

2011 ◽  
Vol 6 (9) ◽  
pp. 2150-2156 ◽  
Author(s):  
Christine A. White ◽  
Andrew D. Rule ◽  
Christine P. Collier ◽  
Ayub Akbari ◽  
John C. Lieske ◽  
...  
Keyword(s):  
Glomerular Filtration Rate ◽  
Glomerular Filtration ◽  
Cystatin C ◽  
Filtration Rate ◽  
Rate Estimation ◽  
Glomerular Filtration Rate Estimation ◽  
The Impact

scholarly journals Urine specific gravity as a diagnostic tool for dehydration in children

2010 ◽  
Vol 50 (5) ◽  
pp. 269 ◽  
Author(s):  
Kalis Joko Purwanto ◽  
Mohammad Juffrie ◽  
Djauhar Ismail
Keyword(s):  
Weight Loss ◽  
Body Weight ◽  
Specific Gravity ◽  
Diagnostic Tool ◽  
Clinical Judgment ◽  
Plasma Osmolality ◽  
Body Weight Loss ◽  
Urine Osmolality ◽  
Urine Specific Gravity ◽  
Urine Production

Background Using clinical judgment to diagnose dehydration can be highly subjective. To diagnose dehydration, it would be ideal to have an accurate, inexpensive, objective and easy-to-perform diagnostic tool. In cases of dehydration, plasma osmolality rises, causing an increase in antidiuretic hormone (ADH) secretion. The increased ADH reduces urine production and increases urine osmolality. Previous studies have show that urine osmolality correlates well to urine specific gravity. We investigated if urine specific gravity can be a reliable and objective detennination of dehydration status.Objective To assess the accuracy of using urine specific gravity as a diagnostic tool to determine dehydration status of children with diarrhea.Methods We conducted the study in the pediatric ward of Sardjito Hospital from September 2009 to December 2009. Using a refractometer we measured urine specific gravity from patients with diarrhea. This measurement was then compared to a standard of acute body weight loss, with dehydration defined as weight loss of 5% or more. The cut-off value for defining dehydration using specific gravity measurements was detennined by a receiver-operator curve (ROC).Results Out of 61 pediatric patients who were recruited in this study, 18 (30%) had dehydration as defined by a body weight loss of 5% or more. Based on the ROC, we determined the cut off  value for urine specific gravity to be 1.022. Using this value, urine specific gravity was 72% sensitive (95% CI 52 to 93), and 84% specific (95% CI 73 to 95) in determining dehydration status.Conclusion Urine specific gravity is less accurate than clinical judgment in determining dehydration status in children with diarrhea.

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