Role of carbonic anhydrase in bone resorption induced by 1,25 dihydroxyvitamin D3 in vitro

• Published in: Calcified tissue international Vol. 37; no. 2; p. 134
• Main Authors: Hall, G.E, Kenny, A.D
• Format: Journal Article
• Language: English
• Published: United States 01.03.1985
• Subjects: 1,25-DIHYDROXYCHOLECALCIFEROL; Acetazolamide - pharmacology; Acid Phosphatase - metabolism; Alkaline Phosphatase - metabolism; Animals; Bone and Bones - enzymology; BONE DISEASES; Bone Resorption - chemically induced; Bone Resorption - drug effects; Bone Resorption - enzymology; Calcitriol - antagonists & inhibitors; Calcium - metabolism; CARBONATE DEHYDRATASE; CARBONATE DESHYDRATASE; CARBONATO DEHIDRATASA; Carbonic Anhydrases - physiology; ENFERMEDADES OSEAS; Kinetics; Mice; Organ Culture Techniques; OSTEOPATHIE; Sulfonamides - pharmacology
• ISSN: 0171-967X; 1432-0827
• DOI: 10.1007/BF02554832

The present investigation was undertaken to study the role of carbonic anhydrase in 1,25 dihydroxyvitamin D3-induced bone resorption. Calvaria were removed from 5- to 6-day-old mice and cultured for periods up to 96 h in Dulbecco's Modified Eagle Medium (high glucose, 4,500 mg/dl) supplemented with antibiotics and either heat-inactivated horse and fetal calf sera or bovine serum albumin. The experimental cultures contained 1 X 10(-8) M 1,25 dihydroxyvitamin D3 (1,25(OH)2D3). All cultures were incubated at 37 degrees C in 5% CO2/95% air. Bone resorption was assessed by release of stable calcium into the medium. Bone enzymes (acid and alkaline phosphatases and carbonic anhydrase) were determined following homogenization in 0.25 M sucrose. The effects of 1,25(OH)2D3 were studied in the presence and absence of the carbonic anhydrase inhibitor acetazolamide and its analogue (CL 13,850), which lacks inhibitory activity. Acetazolamide inhibited 1,25(OH)2D3-induced calcium release in a dose-dependent fashion from 10(-5)-10(-4)M. When added to the cultures at a concentration of 1 X 10(-4)M, acetazolamide completely blocked the 1,25(OH)2D3-induced calcium release, a phenomenon not seen with an equimolar concentration of CL 13,850. The most significant finding was that 1,25(OH)2D3-induced calcium release was accompanied by a significant increase in the carbonic anhydrase activity of bone at both 48 (treated/control ratio = 2.05) and 96 (treated/control ratio = 2.59) hours.