TY - JOUR
T1 - Oxytocin can regulate myometrial smooth muscle excitability by inhibiting the Na + -activated K + channel, Slo2.1
AU - Ferreira, Juan J.
AU - Butler, Alice
AU - Stewart, Richard
AU - Gonzalez-Cota, Ana Laura
AU - Lybaert, Pascale
AU - Amazu, Chinwendu
AU - Reinl, Erin L.
AU - Wakle-Prabagaran, Monali
AU - Salkoff, Lawrence
AU - England, Sarah K.
AU - Santi, Celia M.
N1 - Funding Information:
This work was supported by Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) R01 HD088097 to CMS and SKE as well as (NIGMS and NIMH) R01 GM114694 and R21MH107955 to LS, respectively. A CONACyT Postdoctoral Fellowship EPE-2016291121 and EPE-2017 291231 to AG also funded this work. We thank Dr Deborah Frank for critical review of the manuscript and the Clinical Research Nurses in the Department of Obstetrics and Gynecology for gaining the consent of patients and acquiring myometrial biopsies.
Publisher Copyright:
© 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society
PY - 2019/1/1
Y1 - 2019/1/1
N2 - Key points: At the end of pregnancy, the uterus transitions from a quiescent state to a highly contractile state. This transition requires that the uterine (myometrial) smooth muscle cells increase their excitability, although how this occurs is not fully understood. We identified SLO2.1, a potassium channel previously unknown in uterine smooth muscle, as a potential significant contributor to the electrical excitability of myometrial smooth muscle cells. We found that activity of the SLO2.1 channel is negatively regulated by oxytocin via Gαq-protein-coupled receptor activation of protein kinase C. This results in depolarization of the uterine smooth muscle cells and calcium entry, which may contribute to uterine contraction. These findings provide novel insights into a previously unknown mechanism by which oxytocin may act to modulate myometrial smooth muscle cell excitability. Our findings also reveal a new potential pharmacological target for modulating uterine excitability. Abstract: During pregnancy, the uterus transitions from a quiescent state to a more excitable contractile state. This is considered to be at least partly a result of changes in the myometrial smooth muscle cell (MSMC) resting membrane potential. However, the ion channels controlling the myometrial resting membrane potential and the mechanism of transition to a more excitable state have not been fully clarified. In the present study, we show that the sodium-activated, high-conductance, potassium leak channel, SLO2.1, is expressed and active at the resting membrane potential in MSMCs. Additionally, we report that SLO2.1 is inhibited by oxytocin binding to the oxytocin receptor. Inhibition of SLO2.1 leads to membrane depolarization and activation of voltage-dependent calcium channels, resulting in calcium influx. The results of the present study reveal that oxytocin may modulate MSMC electrical activity by inhibiting SLO2.1 potassium channels.
AB - Key points: At the end of pregnancy, the uterus transitions from a quiescent state to a highly contractile state. This transition requires that the uterine (myometrial) smooth muscle cells increase their excitability, although how this occurs is not fully understood. We identified SLO2.1, a potassium channel previously unknown in uterine smooth muscle, as a potential significant contributor to the electrical excitability of myometrial smooth muscle cells. We found that activity of the SLO2.1 channel is negatively regulated by oxytocin via Gαq-protein-coupled receptor activation of protein kinase C. This results in depolarization of the uterine smooth muscle cells and calcium entry, which may contribute to uterine contraction. These findings provide novel insights into a previously unknown mechanism by which oxytocin may act to modulate myometrial smooth muscle cell excitability. Our findings also reveal a new potential pharmacological target for modulating uterine excitability. Abstract: During pregnancy, the uterus transitions from a quiescent state to a more excitable contractile state. This is considered to be at least partly a result of changes in the myometrial smooth muscle cell (MSMC) resting membrane potential. However, the ion channels controlling the myometrial resting membrane potential and the mechanism of transition to a more excitable state have not been fully clarified. In the present study, we show that the sodium-activated, high-conductance, potassium leak channel, SLO2.1, is expressed and active at the resting membrane potential in MSMCs. Additionally, we report that SLO2.1 is inhibited by oxytocin binding to the oxytocin receptor. Inhibition of SLO2.1 leads to membrane depolarization and activation of voltage-dependent calcium channels, resulting in calcium influx. The results of the present study reveal that oxytocin may modulate MSMC electrical activity by inhibiting SLO2.1 potassium channels.
KW - Myometrium
KW - Oxytocin
KW - SLO2.1 Potassium channels
KW - Smooth muscle
UR - http://www.scopus.com/inward/record.url?scp=85056821056&partnerID=8YFLogxK
U2 - 10.1113/JP276806
DO - 10.1113/JP276806
M3 - Article
C2 - 30334255
AN - SCOPUS:85056821056
SN - 0022-3751
VL - 597
SP - 137
EP - 149
JO - Journal of Physiology
JF - Journal of Physiology
IS - 1
ER -