Distribution of prostaglandin E2 and prostaglandin F2 alpha receptors in human myometrium.

Human myometrium was studied for specific binding of PGE2 and PGF2 alpha. PGF2 alpha-binding was almost undetectable, but specific binding sites for PGE2 with high affinity (KD = 2.7 +/- 0.4 x 10(-9) M were demonstrated. The binding capacity for PGE2 exhibited a topically different distribution pattern with the highest values in the central parts and low to undetectable levels in the cervical region. Binding characteristics were analyzed by receptor kinetics, revealing a homogeneous receptor population. Binding capacity in uteri obtained from post-menopausal women was of the order of 900-940 fmol/mg protein. Oestrogen pre-treatment and pregnancy were associated with a 3-fold reduction of the PGE2-binding capacity.