Calmodulin concentration in the uterus during pregnancy and influence of sex steroids.

Calmodulin concentration in pregnant rat uteri increased gradually and reached a level about three times that in non-pregnant rat at term. In human beings, uterine calmodulin content at term was about three times that in non-pregnant uteri, but there was no significant difference between the levels in uteri at term with and without labor pain. Estrogen increased the rat uterine calmodulin concentration, but progesterone did not change it.