Calmodulin content in human prolactin-secreting pituitary adenoma: an inverse relationship to serum prolactin levels.

Calmodulin content was evaluated in 3 prolactin-secreting pituitary adenomas (prolactinoma) and 3 normal anterior pituitary glands. The calmodulin content in the normal anterior pituitary tissue was quite consistent, 3.32 +/- 0.016 micrograms/mg protein. In contrast, calmodulin content varied almost 4-fold in the prolactinoma tissue (10.97, 8.50 and 3.00 micrograms/mg protein). Preoperative serum prolactin levels varied inversely with the prolactinoma calmodulin content (125, 257 and 3526 ng/ml, respectively). This study reveals that prolactinoma calmodulin content differs from normal, although it is not uniformly elevated as in other transformed tissues and that elevation of prolactinoma calmodulin content does not positively correlate with serum prolactin levels.