Renal and Hormonal Effects of Water Deprivation in Late-Term Pregnant Rats

Salas, Sofía P.; Giacaman, Arturo; Vío, Carlos P.

doi:10.1161/01.hyp.0000138405.94275.a2

Cited by 14 publications

(16 citation statements)

References 20 publications

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“…In the present study, we confirmed earlier work showing that plasma volume expansion increase in a cumulative manner during pregnancy (2,7,26,27). Unexpectedly, we found that ENaC inhibition resulted in an increase in plasma volume in virgin rats, which we attribute to a rebound effect since this is the opposite of what would be expected with ENaC inhibition.…”

Section: Discussionsupporting

confidence: 93%

“…collecting duct; plasma volume expansion; sodium retention IN HUMANS AND RATS, PREGNANCY is accompanied by marked changes in cardiovascular function, renal function, and fluid homeostasis. These adaptations permit an increase in blood volume that will supply the growing uterus and fetus without the development of maternal hypertension.A normal healthy pregnancy is associated with a cumulative plasma volume expansion (PVE) (30 -50%) and avid sodium retention (2,26,27). Failure of this adaptation is associated with maternal morbidity/mortality and intrauterine growth restriction (3, 27).…”

mentioning

confidence: 99%

“…A normal healthy pregnancy is associated with a cumulative plasma volume expansion (PVE) (30 -50%) and avid sodium retention (2,26,27). Failure of this adaptation is associated with maternal morbidity/mortality and intrauterine growth restriction (3, 27).…”

mentioning

confidence: 99%

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Increased renal α-epithelial sodium channel (ENAC) protein and increased ENAC activity in normal pregnancy

West

Zhang

Ecker

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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West C, Zhang Z, Ecker G, Masilamani SM. Increased renal ␣-epithelial sodium channel (ENAC) protein and increased ENAC activity in normal pregnancy. Am J Physiol Regul Integr Comp Physiol 299: R1326 -R1332, 2010. First published August 4, 2010 doi:10.1152/ajpregu.00082.2010.-Pregnancy-mediated sodium (Na) retention is required to provide an increase in plasma volume for the growing fetus. The mechanisms responsible for this Na retention are not clear. We first used a targeted proteomics approach and found that there were no changes in the protein abundance compared with virgin rats of the ␤ or ␥ ENaC, type 3 Na ϩ /H ϩ exchanger (NHE3), bumetanide-sensitive cotransporter (NKCC2), or NaCl cotransporter (NCC) in mid-or late pregnancy. In contrast, we observed marked increases in the abundance of the ␣-ENaC subunit. The plasma volume increased progressively during pregnancy with the greatest plasma volume being evident in late pregnancy. ENaC inhibition abolished the difference in plasma volume status between virgin and pregnant rats. To determine the in vivo activity of ENaC, we conducted in vivo studies of rats in late pregnancy (days 18 -20) and virgin rats to measure the natriuretic response to ENaC blockade (with benzamil). The in vivo activity of ENaC (UNaV postbenzamil-UNaV postvehicle) was markedly increased in late pregnancy, and this difference was abolished by pretreatment with the mineralocorticoid receptor antagonist, eplerenone. These findings demonstrate that the increased ␣-ENaC subunit of pregnancy is associated with an mineralocorticoid-dependent increase in ENaC activity. Further, we show that ENaC activity is a major contributor of plasma volume status in late pregnancy. These changes are likely to contribute to the renal sodium retention and plasma volume expansion required for an optimal pregnancy. collecting duct; plasma volume expansion; sodium retention IN HUMANS AND RATS, PREGNANCY is accompanied by marked changes in cardiovascular function, renal function, and fluid homeostasis. These adaptations permit an increase in blood volume that will supply the growing uterus and fetus without the development of maternal hypertension.A normal healthy pregnancy is associated with a cumulative plasma volume expansion (PVE) (30 -50%) and avid sodium retention (2,26,27). Failure of this adaptation is associated with maternal morbidity/mortality and intrauterine growth restriction (3, 27). Despite the progressive PVE, there is no increase in maternal blood pressure due to a marked decrease in total peripheral vascular resistance (2, 7).Renal sodium excretion determines volume homeostasis and the progressive PVE of normal pregnancy must reflect net renal sodium retention. Alexander et al.(1) performed balance studies in the pregnant rat that demonstrated cumulative sodium retention during pregnancy. The reabsorption of sodium along the renal tubule is determined by the regulation of the individual tubular cotransporters and channels (16), such that a change in the activity of any transporter or channel...

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Section: Discussionsupporting

confidence: 93%

mentioning

confidence: 99%

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Increased renal α-epithelial sodium channel (ENAC) protein and increased ENAC activity in normal pregnancy

West

Zhang

Ecker

et al. 2010

American Journal of Physiology-Regulatory, Integrative and Comp

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“…The expansion of plasma volume begins from the first trimester of gestation, increasing up to 1,250 ml in the third trimester [20] . Several studies have determined the importance of maternal adaptation to hemodynamic changes [21] and the relationship between inadequate adaptation in the early stages of pregnancy and reduced fetal growth [22][23] .…”

Section: Introductionmentioning

confidence: 99%

Body Composition of Women with Newborns Who Are Small for Gestational Age

Levario-Carrillo¹,

Rodríguez²,

Tufiño-Olivares³

et al. 2008

Neonatology

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Background: The relationship between maternal and placental hemodynamic disorders and fetal growth is well known, but few studies have evaluated a link between maternal extracellular water (EW) and newborn birth weight. Objective: To identify the characteristics of body composition (BC) of women with small for gestational age (SGA) newborns, and to determine the relationship between maternal EW and birth weight of the baby. Methods: We studied maternal BC using multifrequency bioelectric impedance in the second and third trimesters of pregnancy. Newborns with weight below the 10th percentile were classified as SGA; those with weights between the 10th and 90th percentiles as appropriate for gestational age (AGA), and large for gestational age (LGA) were those with weights above the 90th percentile. Results: We studied 460 women and their BC varied depending on whether their newborns were SGA, AGA or LGA. EW was lower in the mothers of SGA (11 ± 2 l) compared to AGA (12 ± 3 l) newborns (p < 0.01). We identified a significant relationship (p < 0.01) between maternal EW in the second trimester and the weight of the newborn, β = 43 (95% CI 27–58). Conclusion: BC of women whose newborns are SGA differs significantly from that of women whose newborns are AGA, a result which suggests that the mothers of SGA infants may have a disordered hemodynamic state during the second trimester of pregnancy.

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“…Inadequate volume expansion is associated with pregnancies compromised by fetal growth restriction (3,31). Furthermore, prevention of PVE through restriction of either sodium or water intake during late pregnancy in the rat results in growthrestricted pups (28,30).…”

mentioning

confidence: 99%

Chronic vasodilation increases renal medullary PDE5A and α-ENaC through independent renin-angiotensin-aldosterone system pathways

West

Shaw

Sasser

et al. 2013

American Journal of Physiology-Regulatory, Integrative and Comp

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West CA, Shaw S, Sasser JM, Fekete A, Alexander T, Cunningham MW Jr, Masilamani SM, Baylis C. Chronic vasodilation increases renal medullary PDE5A and ␣-ENaC through independent renin-angiotensin-aldosterone system pathways. via diet], enalapril (ENAL; angiotensin-converting enzyme inhibitor, 62.5 mg/l via water), or vehicle (CON). Mean arterial pressure (MAP) was reduced 7.4 Ϯ 0.5% with NIF, 6.33 Ϯ 0.5% with NIF ϩ SPR, 13.3 Ϯ 0.9% with NIF ϩ LOS, and 12.0 Ϯ 0.4% with ENAL vs. baseline MAP. Compared with CON (3.6 Ϯ 0.3%), plasma volume factored for body weight was increased by NIF (5.2 Ϯ 0.4%) treatment but not by NIF ϩ SPR (4.3 Ϯ 0.3%), NIF ϩ LOS (3.6 Ϯ 0.1%), or ENAL (4.0 Ϯ 0.3%). NIF increased PDE5A protein abundance in the renal inner medulla, and SPR did not prevent this increase (188 Ϯ 16 and 204 Ϯ 22% of CON, respectively). NIF increased the ␣-subunit of the epithelial sodium channel (␣-ENaC) protein in renal outer (365 Ϯ 44%) and inner (526 Ϯ 83%) medulla, and SPR prevented these changes. There was no change in either PDE5A or ␣-ENaC abundance vs. CON in rats treated with NIF ϩ LOS or ENAL. These data indicate that the PVE and renal medullary adaptations in response to chronic vasodilation result from RAAS signaling, with increases in PDE5A mediated through AT 1 receptor and ␣-ENaC through the MR.

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Renal and Hormonal Effects of Water Deprivation in Late-Term Pregnant Rats

Cited by 14 publications

References 20 publications

Increased renal α-epithelial sodium channel (ENAC) protein and increased ENAC activity in normal pregnancy

Increased renal α-epithelial sodium channel (ENAC) protein and increased ENAC activity in normal pregnancy

Body Composition of Women with Newborns Who Are Small for Gestational Age

Chronic vasodilation increases renal medullary PDE5A and α-ENaC through independent renin-angiotensin-aldosterone system pathways

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