Hormone-responsive adenylyl cyclase in the human fallopian tube

Hormone-responsive adenylyl cyclase (AC) activity in biopsies from normal human Fallopian tubes was studied. Enzyme activity with a Km of 0.15 mmol/L and a maximum velocity of 13.8 pmol/mg.min in the basal condition was demonstrated. The addition of prostaglandin E1 (PGE1), PGE2, PGF2a, vasoactive intestinal polypeptide, isoproterenol, and terbutaline increased enzyme activity, with no change in the Km. Maximum stimulation of AC activity was obtained with PGE1, resulting in a 2- to 8-fold increase in AC activity. The response of AC to PGE1 revealed a possible topographical variation, with lowest responses to PGE1 in the isthmus. No such segmental variation in AC activity and response was seen after stimulation with PGF2a, vasoactive intestinal polypeptide, or isoproterenol.