Biological properties of salmon calcitonin IV

In this study we characterized the biological activity of the recently iden tified salmon calcitonin (sCT) IV, in order to evaluate its potential thera peutic value. In the rat bioassay, sCT IV exhibited a 30% higher hypocalcem ic activity than sCT I. The capacity of the molecule to inhibit bone resorp tion was assessed in vitro by the bone resorbing assay and the pit assay, A n inhibitory effect, similar to that of sCT I, was observed in both assays. The interaction of sCT IV with the rabbit CT receptor was also studied, Th e affinity of sCT IV for the receptor was similar to that of sCT I, as was the potency for stimulating cAMP production, The antigenicity of the two mo lecules was not identical. Thus, this new CT could represent a useful novel therapeutic agent for the treatment of bone disorders.