Abstract
Uterine smooth muscle must remain essentially quiescent as it grows and stretches during gestation, but must become highly contractile in labor; the mechanisms responsible for this change in contractility are unknown. Resting membrane potential is a key determinant of excitability in a variety of cell types; because potassium channels can set resting membrane potential in many types of cells, these channels may be important in regulating cellular activity. Two pore‐domain potassium (K2P) channels exhibit small, non‐inactivating “leak” currents which are sensitive to pH, arachidonic acid, certain ions, anandimide, and stretch. Using Western blot and immunofluorescence assays we have found 3 types of K2P channels in nonpregnant mouse myometrial tissues and cells – TASK‐1, TASK‐2, and TREK‐1. The expression of TASK‐1 and TREK‐1 was significantly reduced in pregnant myometrium, with the largest reduction occurring between days 10 and 15 of pregnancy. Pregnancy‐associated reductions in TASK‐1 and TREK‐1 were not observed in heart, brain, kidney, liver, or gastrointestinal smooth muscle. These findings not only suggest that K2P channels may be involved in the regulation of contractions in the nonpregnant myometrium, but that changes in the expression of these channels could be responsible for changes in contractility in pregnant myometrium.
(Supported by Creighton University Health Futures Foundation.)