A large, sustained plasma volume expansion (PVE) is a necessary feature of normal, successful pregnancy. Suboptimal PVE is associated with adverse fetal outcome, and is a component of preeclampsia. The goal of this project is to determine the primary mechanism of the normal gestational PVE, so that ultimately, complications of pregnancy associated with failure to PVE can be prevented. This proposal is motivated by several marked similarities between the renal and hemodynamic responses to normal pregnancy, and those seen in states of inappropriate PVE, such as nephrosis or cirrhosis. The primary renal mechanism in pathological sodium retention is a failure of natriuretic mechanisms that rely on cGMP as second messenger, due to increased cGMP hydrolysis by phosphodiesterase (PDE). Here, we will test the hypothesis that selective upregulation of the renal tubular PDE system (particularly the inner medullary collecting duct, IMCD) occurs in pregnancy and causes widespread refractoriness to natriuretic stimuli, such as acute volume expansion and administered atrial natriuretic peptide, leading to PVE. We will also characterize the isoforms and location in the kidney of the PDEs involved in the renal response to normal P and determine whether increased renal PDE activity in pregnancy results from translational or posttranslational events. We will investigate how angiotensin II and renal nerve activity (major renal sodium retaining systems) are involved; we will test the """"""""underfill"""""""" hypothesis of gestational PVE and we will determine whether the maternal hormones progesterone, prolactin or relaxin are primarily responsible for the increased renal PDE activity and PVE of P. Finally, we will chronically and locally inhibit the relevant PDE(s) during pregnancy to establish the impact on maternal hemodynamics and fetal outcome. All studies will be in rat, using a combination of in vivo techniques to measure renal sodium handling capacity and in vitro techniques on isolated glomeruli, proximal tubules and inner medullary collecting duct cells, to include enzyme activity assays, Western blot, immunocytochemistry, Northern blot or RNAse protection assay and in situ hybridization. ? ?

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Project (R01)
Project #
5R01HD041571-05
Application #
7428841
Study Section
General Medicine B Study Section (GMB)
Program Officer
Ilekis, John V
Project Start
2004-08-10
Project End
2010-05-31
Budget Start
2008-06-01
Budget End
2010-05-31
Support Year
5
Fiscal Year
2008
Total Cost
$253,536
Indirect Cost
Name
University of Florida
Department
Physiology
Type
Schools of Medicine
DUNS #
969663814
City
Gainesville
State
FL
Country
United States
Zip Code
32611
West, Crystal A; Verlander, Jill W; Wall, Susan M et al. (2015) The chloride-bicarbonate exchanger pendrin is increased in the kidney of the pregnant rat. Exp Physiol 100:1177-86
West, Crystal A; McDonough, Alicia A; Masilamani, Shyama M E et al. (2015) Renal NCC is unchanged in the midpregnant rat and decreased in the late pregnant rat despite avid renal Na+ retention. Am J Physiol Renal Physiol 309:F63-70
West, Crystal A; Shaw, Stefan; Sasser, Jennifer M et al. (2013) Chronic vasodilation increases renal medullary PDE5A and *-ENaC through independent renin-angiotensin-aldosterone system pathways. Am J Physiol Regul Integr Comp Physiol 305:R1133-40
Cunningham Jr, Mark W; Sasser, Jennifer M; West, Crystal A et al. (2013) Renal redox response to normal pregnancy in the rat. Am J Physiol Regul Integr Comp Physiol 304:R443-9
Fekete, Andrea; Sasser, Jennifer M; Baylis, Chris (2011) Chronic vasodilation produces plasma volume expansion and hemodilution in rats: consequences of decreased effective arterial blood volume. Am J Physiol Renal Physiol 300:F113-8
Sasser, Jennifer M; Ni, Xi-Ping; Humphreys, Michael H et al. (2010) Increased renal phosphodiesterase-5 activity mediates the blunted natriuretic response to a nitric oxide donor in the pregnant rat. Am J Physiol Renal Physiol 299:F810-4
Sasser, Jennifer M; Baylis, Chris (2010) Effects of sildenafil on maternal hemodynamics and fetal growth in normal rat pregnancy. Am J Physiol Regul Integr Comp Physiol 298:R433-8
Sasser, Jennifer M; Baylis, Chris (2008) The natriuretic and diuretic response to dopamine is maintained during rat pregnancy. Am J Physiol Renal Physiol 294:F1342-4
Knight, Sarah; Snellen, Harold; Humphreys, Michael et al. (2007) Increased renal phosphodiesterase-5 activity mediates the blunted natriuretic response to ANP in the pregnant rat. Am J Physiol Renal Physiol 292:F655-9
Ni, Xi-Ping; Safai, Massy; Rishi, Rahul et al. (2004) Increased activity of cGMP-specific phosphodiesterase (PDE5) contributes to resistance to atrial natriuretic peptide natriuresis in the pregnant rat. J Am Soc Nephrol 15:1254-60