Editing Gap junction (section)

====Uterus====
The [[Uterus|uterine]] muscle ([[myometrium]]) remains in a quiescent relaxed state during [[pregnancy]] to maintain [[fetal development]]. Immediately preceding [[Childbirth|labor]], the myometrium transforms into an activated contractile unit by increasing expression of [[GJA1|connexin-43]] ([[Cx43|CX43]], a.k.a. Gap Junction Alpha-1 protein, [[GJA1]]) facilitating gap junction (GJ) formation between individual myometrial cells. Importantly, the formation of GJs promotes communication between neighbouring [[Muscle cell|myocytes]], which facilitates the transfer of small molecules such as secondary messengers, metabolites, and small ions for electrical coupling. Consistent with all species, uterine myometrial contractions propagate from spontaneous [[action potential]]s as a result of sudden change in [[Cell membrane|plasma membrane]] permeability. This leads to an increase of intracellular [[Ca²⁺]] concentration, facilitating action potential propagation through electrically coupled cells.<ref>Garfield, RE; Sims, SM; Kannan, MS; Daniel, EE (November 1978). "Possible role of gap junctions in activation of myometrium during parturition". ''Am. J. Physiol''. '''235''' (5): C168–79. [https://journals.physiology.org/doi/abs/10.1152/ajpcell.1978.235.5.C168 doi:10.1152/ajpcell.1978.235.5.C168]. PMID 727239. S2CID [https://www.semanticscholar.org/paper/Possible-role-of-gap-junctions-in-activation-of-Garfield-Sims/ce78aa441efb2f15ff4749d082197ed4db1b2584 31610495]</ref> It has more recently been discovered that uterine [[macrophage]]s directly physically couples with uterine myocytes through CX43, transferring Ca²⁺, to promote uterine muscle contraction and excitation during labor onset.<ref>Boros-Rausch, A., Shynlova, O., & Lye, S. J. (2021). "A Broad-Spectrum Chemokine Inhibitor Blocks Inflammation-Induced Myometrial Myocyte-Macrophage Crosstalk and Myometrial Contraction". ''Cells''. '''11''' (1): 128. [https://www.mdpi.com/2073-4409/11/1/128 doi: 10.3390/cells11010128] PMID 35011690</ref>