Biomaterial Database

Interaction between 24R,25-dihydroxycholecalciferol and 1,25-dihydroxycholecalciferol on 45Ca release from bone in vitro. 1981

A Mahgoub

Interaction among vitamin D3 metabolites on bone receptor sites is not known. Therefore, interaction between the most potent vitamin D3 metabolite, 1,25(OH)2D3, and the most abundant dihydroxymetabolite, 24R,25(OH)2D3, was studied on isolated rat fetal bone by measuring 45Ca release from prelabeled bones. 24R,25(OH)2D3 at concentrations of 10-50 ng/ml caused marked inhibition of the bone-resorbing activity of 1,25(OH)2D3 at concentrations of 10-50 pg/ml. 24S,25(OH)2 (unnatural enantiometer), on the other hand, at a concentration of 100 ng/ml did not inhibit the bone-resorbing effect of 10 pg/ml 1,25(OH)2D3. 24R,25(OH)2D3 at a concentration of 20 ng/ml did not inhibit the 45Ca-releasing effect of a submaximal concentration of PTH (500 ng/ml). Therefore, the inhibitory effect of 24R,25(OH)2D3 on the bone response to 1,25(OH)2D3 appeared to be specific and probably due to a competitive inhibitory effect. In addition, the inhibitory effect of 24R,25(OH)2D3 was weak, since it could be partially overcome by increasing the concentration of 1,25(OH)2D3.

UI	MeSH Term	Description	Entries
D010281	Parathyroid Hormone	A polypeptide hormone (84 amino acid residues) secreted by the PARATHYROID GLANDS which performs the essential role of maintaining intracellular CALCIUM levels in the body. Parathyroid hormone increases intracellular calcium by promoting the release of CALCIUM from BONE, increases the intestinal absorption of calcium, increases the renal tubular reabsorption of calcium, and increases the renal excretion of phosphates.	Natpara,PTH (1-84),PTH(1-34),Parathormone,Parathyrin,Parathyroid Hormone (1-34),Parathyroid Hormone (1-84),Parathyroid Hormone Peptide (1-34),Hormone, Parathyroid
D001842	Bone and Bones	A specialized CONNECTIVE TISSUE that is the main constituent of the SKELETON. The principal cellular component of bone is comprised of OSTEOBLASTS; OSTEOCYTES; and OSTEOCLASTS, while FIBRILLAR COLLAGENS and hydroxyapatite crystals form the BONE MATRIX.	Bone Tissue,Bone and Bone,Bone,Bones,Bones and Bone,Bones and Bone Tissue,Bony Apophyses,Bony Apophysis,Condyle,Apophyses, Bony,Apophysis, Bony,Bone Tissues,Condyles,Tissue, Bone,Tissues, Bone
D001862	Bone Resorption	Bone loss due to osteoclastic activity.	Bone Loss, Osteoclastic,Osteoclastic Bone Loss,Bone Losses, Osteoclastic,Bone Resorptions,Loss, Osteoclastic Bone,Losses, Osteoclastic Bone,Osteoclastic Bone Losses,Resorption, Bone,Resorptions, Bone
D002117	Calcitriol	The physiologically active form of vitamin D. It is formed primarily in the kidney by enzymatic hydroxylation of 25-hydroxycholecalciferol (CALCIFEDIOL). Its production is stimulated by low blood calcium levels and parathyroid hormone. Calcitriol increases intestinal absorption of calcium and phosphorus, and in concert with parathyroid hormone increases bone resorption.	1 alpha,25-Dihydroxycholecalciferol,1 alpha,25-Dihydroxyvitamin D3,1, 25-(OH)2D3,1,25(OH)2D3,1,25-Dihydroxycholecalciferol,1,25-Dihydroxyvitamin D3,1 alpha, 25-dihydroxy-20-epi-Vitamin D3,1,25(OH)2-20epi-D3,1,25-dihydroxy-20-epi-Vitamin D3,20-epi-1alpha,25-dihydroxycholecaliferol,Bocatriol,Calcijex,Calcitriol KyraMed,Calcitriol-Nefro,Decostriol,MC-1288,MC1288,Osteotriol,Renatriol,Rocaltrol,Silkis,Sitriol,Soltriol,Tirocal,1 alpha,25 Dihydroxyvitamin D3,1,25 Dihydroxycholecalciferol,1,25 Dihydroxyvitamin D3,1,25 dihydroxy 20 epi Vitamin D3,Calcitriol Nefro,D3, 1 alpha,25-Dihydroxyvitamin,D3, 1,25-Dihydroxyvitamin,D3, 1,25-dihydroxy-20-epi-Vitamin,KyraMed, Calcitriol,MC 1288
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D004100	Dihydroxycholecalciferols	Cholecalciferols substituted with two hydroxy groups in any position.	Dihydroxyvitamins D
D004305	Dose-Response Relationship, Drug	The relationship between the dose of an administered drug and the response of the organism to the drug.	Dose Response Relationship, Drug,Dose-Response Relationships, Drug,Drug Dose-Response Relationship,Drug Dose-Response Relationships,Relationship, Drug Dose-Response,Relationships, Drug Dose-Response
D004347	Drug Interactions	The action of a drug that may affect the activity, metabolism, or toxicity of another drug.	Drug Interaction,Interaction, Drug,Interactions, Drug
D006887	Hydroxycholecalciferols	Hydroxy analogs of vitamin D 3; (CHOLECALCIFEROL); including CALCIFEDIOL; CALCITRIOL; and 24,25-DIHYDROXYVITAMIN D 3.	Hydroxyvitamins D,Hydroxycholecalciferol
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia