[Cyclic nucleotide content of the rabbit myometrium in various functional states]

Myometrium of female rabbits at the state of functional rest contained 260 pmoles of cAMP per g of tissue and 25 pmoles cGMP. In dynamics of pregnancy content of cAMP was increased up to 400 pmoles/g within the second half of pregnancy; the content of cGMP was decreased down to 10 pmoles/g. During labor content of cAMP and of cGMP became minimal; within the postnatal period concentration of cAMP was increased up to the values observed in the antenatal period and the content of cGMP was unaltered. Under these conditions the content of cAMP, cGMP and the activity of corresponding soluble phosphodiesterases were similarly altered. The regulatory subunit of protein kinase of the type I (RI) was shown to possess two sites for cAMP binding and RII--one site. The data obtained suggest that cyclic nucleotides are important for regulation of the myometrium functional state.