title: Hypocalcemic potency of the ultimobranchial gland in some urodelan amphibians.
abstract: The hypocalcemic potencies of the ultimobranchial glands of two urodelans, Onychodactylus japonicus and Hynobius nigrescens, were studied; according to the rat bioassay, their calcitonin values (MRC) were 30 and 18 mU/kg body wt, respectively. Various organs other than the ultimobranchial gland were also assayed in rats to see whether they had any hypocalcemic potency. However, the ultimobranchial gland was the only organ examined with detectable hypocalcemic potencies in these urodelans. The hypocalcemic potencies of urodelan ultimobranchial glands are one order lower than those reported in the other vertebrate classes, contrasting with the potencies of anuran ultimobranchial glands. The biological significance of this low potency is discussed.
mesh_terms: D000818:Animals; D002116:Calcitonin / Q000008:administration & dosage; D002118:Calcium / Q000097:blood; D006996:Hypocalcemia / Q000209:etiology*; D007700:Kinetics; D010758:Phosphorus / Q000097:blood; D051381:Rats; D014460:Ultimobranchial Body / Q000032:analysis* / Q000502:physiology; D014562:Caudata / Q000502:physiology*
chemical_list: D010758:Phosphorus; D002116:Calcitonin; D002118:Calcium