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Am J Hypertens. 2010 Dec;23(12):1279-85. doi: 10.1038/ajh.2010.195. Epub 2010 Sep 9.

The ouabain-binding site of the α2 isoform of Na,K-ATPase plays a role in blood pressure regulation during pregnancy.

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  • 1Department of Molecular Genetics, Biochemistry, and Microbiology, University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.

Abstract

BACKGROUND:

The cardiotonic steroid/ouabain-binding site of the α subunit of Na,K-ATPase is thought to play an important role in cardiovascular homeostasis. Previously, we demonstrated the cardiotonic steroid-binding site of the α2 Na,K-ATPase is involved in adrenocorticotropic hormone (ACTH)-induced hypertension by using gene-modified α2(R/R) mice in which the cardiotonic steroid-binding site is relatively resistant to ouabain compared to the ouabain-sensitive wild-type α2(S/S) mice. To further explore the importance of this site in the cardiovascular system, we investigated blood pressure regulation during pregnancy in mice with the α2(R/R) isoform.

METHODS:

The systolic blood pressure (SBP) of the α2(S/S) and α2(R/R) mice was measured before and during pregnancy by tail-cuff. The expression of the α isoforms of Na, K-ATPase in various tissues and plasma endogenous ouabain contents were assessed prior to pregnancy as well as days 7 and 17 of gestation.

RESULTS:

The α2(S/S) mice showed a gradual decrease in the SBP during the first two trimesters, followed by an increase above the preconceptional level in the third trimester. However, the α2(R/R) mice exhibited a lower blood pressure in the third trimester. The cardiac expression of the α2 Na,K-ATPase in the α2(S/S) mice was significantly less than that of the α2(R/R) mice throughout the pregnancy. The plasma endogenous ouabain concentration significantly increased by twofold at day 17 of pregnancy in the α2(R/R) mice but not in the α2(S/S) mice.

CONCLUSIONS:

The cardiotonic steroid-binding site of the α2 Na,K-ATPase plays a role in maintaining normal SBP during pregnancy.

PMID:
20940714
[PubMed - indexed for MEDLINE]
PMCID:
PMC3029015
Free PMC Article

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