FIG. 5.

Partial dependence of TSH-induced hormone release on calcium influx through L-type calcium channels but not on protein kinase A in cultured pituitary cells. (A) Basal and TSH-stimulated ACTH (left) and β-endorphin (right) release was evaluated during 7 hours of incubation in the presence and absence of 1 μM nifedipine, a blocker of L-type calcium channels. (B) The lack of effects of H89, a protein kinase A inhibitor, on basal and TSH-stimulated ACTH (left) and β-endorphin (right) release. Color images are available online.