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Activity and protein expression of the Na+/H+ exchanger is reduced in syncytiotrophoblast microvillous plasma membranes isolated from preterm intrauterine growth restriction pregnancies

Johansson, Martin LU ; Glazier, J. D.; Sibley, C. P.; Jansson, T. and Powell, Theresa L. (2002) In Journal of Clinical Endocrinology and Metabolism 87(12). p.5686-5694
Abstract

Regulation of syncytiotrophoblast intracellular pH is critical to optimum enzymatic and transport functions of the placenta. Previous studies of Na+/H+ exchanger (NHE) activity in the placenta from pregnancies complicated by intrauterine growth restriction (IUGR) have produced conflicting results. The possible role of altered placental pH regulation in the development of acidosis in some fetuses subjected to IUGR remains to be fully established. We investigated the activity and protein expression of the NHE in syncytiotrophoblast microvillous (MVM) plasma membranes isolated from preterm and term placentas obtained from uncomplicated and IUGR pregnancies. Western blotting showed that the expression of NHE isoforms... (More)

Regulation of syncytiotrophoblast intracellular pH is critical to optimum enzymatic and transport functions of the placenta. Previous studies of Na+/H+ exchanger (NHE) activity in the placenta from pregnancies complicated by intrauterine growth restriction (IUGR) have produced conflicting results. The possible role of altered placental pH regulation in the development of acidosis in some fetuses subjected to IUGR remains to be fully established. We investigated the activity and protein expression of the NHE in syncytiotrophoblast microvillous (MVM) plasma membranes isolated from preterm and term placentas obtained from uncomplicated and IUGR pregnancies. Western blotting showed that the expression of NHE isoforms 1, 2, and 3 was approximately 10-fold greater in MVM than in basal plasma membrane (BM). Immunohistochemistry localized NHE-1 and NHE-2 to MVM and BM and NHE-3 to the MVM, BM, and cytoplasm of the syncytiotrophoblast. NHE-1 expression in MVM from preterm IUGR placentas was reduced by 55%, compared with gestational age-matched controls (P < 0.05, n = 6 and n = 16, respectively), whereas NHE-1 expression was unaltered in term IUGR placentas (n = 8). The activity (amiloride-sensitive Na+ uptake) of NHE in MVM from IUGR preterm placentas was reduced by 48% (P < 0.05, n = 6). In contrast, MVM NHE activity was unchanged in term IUGR (n = 7). Using Northern blotting, no difference could be demonstrated in NHE-1 mRNA expression between IUGR and control groups. The reduced activity and expression of NHE in MVM of preterm IUGR placentas may compromise placental function and may contribute to the development of fetal acidosis in preterm IUGR fetuses.

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author
publishing date
type
Contribution to journal
publication status
published
in
Journal of Clinical Endocrinology and Metabolism
volume
87
issue
12
pages
5686 - 5694
publisher
The Endocrine Society
external identifiers
  • scopus:0036914927
ISSN
0021-972X
DOI
10.1210/jc.2002-020214
language
English
LU publication?
no
id
45da4988-46b6-4045-9e31-8617afb40ff7
date added to LUP
2017-04-10 16:30:37
date last changed
2017-08-06 05:19:58
@article{45da4988-46b6-4045-9e31-8617afb40ff7,
  abstract     = {<p>Regulation of syncytiotrophoblast intracellular pH is critical to optimum enzymatic and transport functions of the placenta. Previous studies of Na<sup>+</sup>/H<sup>+</sup> exchanger (NHE) activity in the placenta from pregnancies complicated by intrauterine growth restriction (IUGR) have produced conflicting results. The possible role of altered placental pH regulation in the development of acidosis in some fetuses subjected to IUGR remains to be fully established. We investigated the activity and protein expression of the NHE in syncytiotrophoblast microvillous (MVM) plasma membranes isolated from preterm and term placentas obtained from uncomplicated and IUGR pregnancies. Western blotting showed that the expression of NHE isoforms 1, 2, and 3 was approximately 10-fold greater in MVM than in basal plasma membrane (BM). Immunohistochemistry localized NHE-1 and NHE-2 to MVM and BM and NHE-3 to the MVM, BM, and cytoplasm of the syncytiotrophoblast. NHE-1 expression in MVM from preterm IUGR placentas was reduced by 55%, compared with gestational age-matched controls (P &lt; 0.05, n = 6 and n = 16, respectively), whereas NHE-1 expression was unaltered in term IUGR placentas (n = 8). The activity (amiloride-sensitive Na<sup>+</sup> uptake) of NHE in MVM from IUGR preterm placentas was reduced by 48% (P &lt; 0.05, n = 6). In contrast, MVM NHE activity was unchanged in term IUGR (n = 7). Using Northern blotting, no difference could be demonstrated in NHE-1 mRNA expression between IUGR and control groups. The reduced activity and expression of NHE in MVM of preterm IUGR placentas may compromise placental function and may contribute to the development of fetal acidosis in preterm IUGR fetuses.</p>},
  author       = {Johansson, Martin and Glazier, J. D. and Sibley, C. P. and Jansson, T. and Powell, Theresa L.},
  issn         = {0021-972X},
  language     = {eng},
  month        = {12},
  number       = {12},
  pages        = {5686--5694},
  publisher    = {The Endocrine Society},
  series       = {Journal of Clinical Endocrinology and Metabolism},
  title        = {Activity and protein expression of the Na+/H+ exchanger is reduced in syncytiotrophoblast microvillous plasma membranes isolated from preterm intrauterine growth restriction pregnancies},
  url          = {http://dx.doi.org/10.1210/jc.2002-020214},
  volume       = {87},
  year         = {2002},
}