Identification and expression of G-proteins in human myometrium: up-regulation of G alpha s in pregnancy.

We report that human myometrium contains G alpha i1, G alpha i3, and G alpha q, and G alpha 11, which are expressed at similar levels in tissues from pregnant and nonpregnant women. G alpha i2 is also expressed, but at a slightly reduced level, in tissue taken from pregnant compared to nonpregnant donors. The major finding of this investigation is the substantial increase in G alpha s expression in pregnant myometrium. The increase in G alpha s levels may play a crucial role in maintaining relaxation of the uterus by favoring cAMP formation during pregnancy.