Potassium channels and uterine function

Abstract

Ion channels are effector proteins that mediate uterine excitability throughout gestation. This review will focus primarily on the role of potassium channels in regulating myometrial tone in pregnancy and labor contractions. During gestation, potassium channels maintain the uterus in a state of quiescence by contributing to the resting membrane potential and counteracting contractile stimuli. This review summarizes the current knowledge about the significance of the potassium channels in maintaining a normal gestational period and initiating labor contractions at term.

Figure 1

(A) Isoforms of the BKCa channel, mK44, SV1, and STREX are the protein products resulting from alternative splicing of the KCNMA gene. S0-S6 represents hydrophobic transmembrane spanning domains, while S7-S10 represents intracellular hydrophobic domains. (B) Isoforms of the SK3 channel derived from alternative start codons (adapted from 51and 52).

Figure 2

A schematic figure of a myometrial smooth muscle cell showing a variety of ion channels that are involved in regulation of membrane potential and cell excitability. Protein phosphatase (Ptase), myosin light chain kinase (MLCK), phosphorylated myosin light chain kinase (MLCK-P), calcium calmodulin-dependent protein kinase (CamK), Kv channel interacting protein (KChIP).