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Na+-K+-ATPase is distributed to microvillous and basal membrane of the syncytiotrophoblast in human placenta

Johansson, Martin LU ; Jansson, T. LU and Powell, T. L. (2000) In American Journal of Physiology - Regulatory Integrative and Comparative Physiology 279(1 48-1). p.287-294
Abstract

Despite its importance for placental function, syncytiotrophoblast Na+-K+-ATPase has not been studied in detail. We purified syncytiotrophoblast microvillous (MVM) and basal (BM) membranes from full-term human placenta. Western blotting with isoform-specific antibodies demonstrated the presence of the α1-subunit, but not the α2- or α3-subunits, in MVM and BM. Relative density per unit membrane protein in BM was 48 ± 1% (mean ± SE, n = 4, P < 0.02) of that in the MVM. The activity of Na+-K+-ATPase was lower in BM (1.4 ± 0.14 μmol · mg-1 · min-1, n = 8, P < 0.02) than in MVM (3.9 ± 0.25 μmol · mg-1 · min-1).... (More)

Despite its importance for placental function, syncytiotrophoblast Na+-K+-ATPase has not been studied in detail. We purified syncytiotrophoblast microvillous (MVM) and basal (BM) membranes from full-term human placenta. Western blotting with isoform-specific antibodies demonstrated the presence of the α1-subunit, but not the α2- or α3-subunits, in MVM and BM. Relative density per unit membrane protein in BM was 48 ± 1% (mean ± SE, n = 4, P < 0.02) of that in the MVM. The activity of Na+-K+-ATPase was lower in BM (1.4 ± 0.14 μmol · mg-1 · min-1, n = 8, P < 0.02) than in MVM (3.9 ± 0.25 μmol · mg-1 · min-1). Immunocytochemistry confirmed the distribution of Na+-K+-ATPase to MVM and BM. These findings suggest that the syncytiotrophoblast represents a type of transporting epithelium different from the classical epithelia found in the small intestine and kidney, where Na+-K+-ATPase is confined to the basolateral membrane only. This unique polarization of the Na+ pump does not, however, preclude a net transcellular transport of Na+ to the fetus.

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author
publishing date
type
Contribution to journal
publication status
published
keywords
3-O-methylfluorescein phosphate, Fetus, Sodium transport
in
American Journal of Physiology - Regulatory Integrative and Comparative Physiology
volume
279
issue
1 48-1
pages
287 - 294
publisher
American Physiological Society
external identifiers
  • scopus:0033899966
ISSN
0363-6119
language
English
LU publication?
no
id
78e294b9-faa1-4a1f-b494-d3fd2c23071b
date added to LUP
2017-04-10 16:50:58
date last changed
2017-08-27 06:39:06
@article{78e294b9-faa1-4a1f-b494-d3fd2c23071b,
  abstract     = {<p>Despite its importance for placental function, syncytiotrophoblast Na<sup>+</sup>-K<sup>+</sup>-ATPase has not been studied in detail. We purified syncytiotrophoblast microvillous (MVM) and basal (BM) membranes from full-term human placenta. Western blotting with isoform-specific antibodies demonstrated the presence of the α<sub>1</sub>-subunit, but not the α<sub>2</sub>- or α<sub>3</sub>-subunits, in MVM and BM. Relative density per unit membrane protein in BM was 48 ± 1% (mean ± SE, n = 4, P &lt; 0.02) of that in the MVM. The activity of Na<sup>+</sup>-K<sup>+</sup>-ATPase was lower in BM (1.4 ± 0.14 μmol · mg<sup>-1</sup> · min<sup>-1</sup>, n = 8, P &lt; 0.02) than in MVM (3.9 ± 0.25 μmol · mg<sup>-1</sup> · min<sup>-1</sup>). Immunocytochemistry confirmed the distribution of Na<sup>+</sup>-K<sup>+</sup>-ATPase to MVM and BM. These findings suggest that the syncytiotrophoblast represents a type of transporting epithelium different from the classical epithelia found in the small intestine and kidney, where Na<sup>+</sup>-K<sup>+</sup>-ATPase is confined to the basolateral membrane only. This unique polarization of the Na<sup>+</sup> pump does not, however, preclude a net transcellular transport of Na<sup>+</sup> to the fetus.</p>},
  author       = {Johansson, Martin and Jansson, T. and Powell, T. L.},
  issn         = {0363-6119},
  keyword      = {3-O-methylfluorescein phosphate,Fetus,Sodium transport},
  language     = {eng},
  number       = {1 48-1},
  pages        = {287--294},
  publisher    = {American Physiological Society},
  series       = {American Journal of Physiology - Regulatory Integrative and Comparative Physiology},
  title        = {Na+-K+-ATPase is distributed to microvillous and basal membrane of the syncytiotrophoblast in human placenta},
  volume       = {279},
  year         = {2000},
}