Calcitonin of the stingray: comparison of the hypocalcemic activity with other calcitonins.

Hypocalcemic potency of calcitonin isolated from the stingray (cartilaginous fish), Dasyatis akajei, was examined using the rat bioassay and compared with the activities of other calcitonins (human, pig, salmon, eel, and fowl). The potency of Dasyatis calcitonin (dCT) was estimated to be 1500-3800 IU/mg. However, when the duration of the hypocalcemic effect of dCT was taken into consideration, it was judged that dCT was approximately 2.4-6.2 times more potent than mammalian calcitonins, but about 2.3-3.5 times less active than other nonmammalian calcitonins.