Carbonic anhydrase activity of chick osteoclasts is increased by parathyroid hormone
- Univ. of Pennsylvania School of Medicine, Philadelphia (USA)
Embryonic chick osteoclasts were harvested, cultured for 18 h, and separated from erythrocytes, and carbonic anhydrase (CA) activity was assayed. Cultures contained 75-85% osteoclasts by acid phosphatase stain. CA activity was also determined after exposure to parathyroid hormone (PTH). Two methods of measurement were used: a {Delta}pH method, which detects the generation of hydrogen ion by carbonic anhydrase, and a mass spectrometric method, which follows the disappearance of {sup 18}O-enriched CO{sub 2}. Unstimulated osteoclasts showed CA activity that was one-third that of erythrocytes but was comparable with macrophges and chondrocytes. Osteoclasts exposed to PTH showed a twofold increase in activity, which occurred after 30 min. Ethoxzolamide (10{sup {minus}8} M) inhibited enzyme activity by 90%. Treatment of osteoclasts with calcitonin did not prevent the PTH-associated increase in CA activity. The doubling of CA activity with PTH stimulation supports the hypothesis that osteoclastic CA is intimately involved in bone resorption.
- OSTI ID:
- 6994887
- Journal Information:
- American Journal of Physiology; (USA), Journal Name: American Journal of Physiology; (USA) Vol. 253:6; ISSN 0002-9513; ISSN AJPHA
- Country of Publication:
- United States
- Language:
- English
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59 BASIC BIOLOGICAL SCIENCES
ACID PHOSPHATASE
ALKALI METAL COMPOUNDS
ANIMAL CELLS
ANIMALS
BIODEGRADATION
BIOLOGICAL EFFECTS
BIOLOGICAL MATERIALS
BIRDS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
BONE CELLS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CARBON-OXYGEN LYASES
CARBONATES
CHALCOGENIDES
CHEMICAL REACTIONS
CHICKENS
CONNECTIVE TISSUE CELLS
DECOMPOSITION
EMBRYONIC CELLS
ENZYME ACTIVITY
ENZYMES
ERYTHROCYTES
ESTERASES
EVEN-EVEN NUCLEI
FOWL
HORMONES
HYDRO-LYASES
HYDROLASES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LYASES
MATERIALS
NUCLEI
ORGANS
OXIDES
OXYGEN 18
OXYGEN COMPOUNDS
OXYGEN ISOTOPES
PARATHORMONE
PEPTIDE HORMONES
PH VALUE
PHOSPHATASES
SKELETON
SODIUM CARBONATES
SODIUM COMPOUNDS
SOMATIC CELLS
STABLE ISOTOPES
TRACER TECHNIQUES
VERTEBRATES