Table of Contents
Physiology Journal
Volume 2013, Article ID 584717, 7 pages
http://dx.doi.org/10.1155/2013/584717
Clinical Study

The Small-Conductance Ca2+-Activated Potassium Channel, Subtype SK3, in the Human Myometrium Is Downregulated in Early Stages of Pregnancy

1Department of Physiology, Biochemistry and Nutrition, IKVH, Faculty of Health and Medical Sciences, University of Copenhagen, 7 Grønnegaardsvej, 1870 Frederiksberg C, Denmark
2Department of Clinical Biochemistry, Roskilde Hospital, 7-13 Køgevej, 4000 Roskilde, Denmark
3Smooth Muscle Research Centre, Køge Hospital, 1 Lykkebækvej, 4600 Køge, Denmark
4Department of Gynaecology and Obstetrics, University of Copenhagen, 60 Smedelundsgade, 4300 Holbæk, Denmark
5Department of Endocrinology Research, BMI, Faculty of Health and Medical Sciences, University of Copenhagen, 3 Blegdamsvej, 2200 København N, Denmark

Received 27 December 2012; Revised 12 March 2013; Accepted 12 March 2013

Academic Editor: Germán Vicente-Rodriguez

Copyright © 2013 M. Rahbek et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

The human myometrium is mainly relaxed during pregnancy, but, up to term, contractions become more coordinated and forceful in order to initiate delivery. Small conductance Ca2+-activated K+ channels (SK channels) in human myometrium have been shown to be downregulated in late pregnancy. The aim was to investigate the presence of SK2 and SK3 in the human myometrium from nonpregnant women, pregnant women at term, and pregnancies delivered preterm and, in addition, to characterize the time of downregulation of these channels. Using qRT-PCR, we observed significantly lower levels of mRNA for SK2 than for SK3 in the nonpregnant tissue. The mRNA levels of SK3 were significantly reduced in tissue from pregnancies at term and pregnancies resulting in preterm deliveries, whereas no downregulation for SK2 was observed. Western blotting confirmed the qRT-PCR results. Using immunohistochemical staining, both SK2 and SK3 were detected in endometrial glandular epithelium. We conclude that SK3 mRNA is downregulated early in pregnancy—at least among those that result in preterm deliveries. Furthermore, we find that SK channels are expressed not only in the uterine smooth muscle but also in the endometrial epithelium.