of progesterone production (also ca. 80%) in the cellular response
to db-cAMP in TPA-treated cells (Table 1C).
[
125I]EGF binding to cells preincubated with TPA was reduced
some 65% (Table 2), and progesterone synthesis was also diminished
about 60% as well (Table 1C). These findings indicate that
under these conditions receptor number and steroidogenic responsiveness
are closely coupled. One caveat, however, is that the
relatively low levels of EGF-mediated progesterone synthesis
preclude high accuracy.
Desensitization with TPA followed by a challenge with hCG,