Maintenance by cortisone of the calcemic response to parathyroid extract of rats on a diet without vitamin D and low in calcium.
Weanling rats raised for 21 days on a vitamin D deprived, low Ca diet (0.02%), and given chronic cortisone administration (5 mg/kg/d), maintain responsiveness to the hypercalcemic effect of endogenous and exogenous parathyroid extract (PTE). The PTE action is a bone effect that does not require the presence of the kidneys, and is not related to a higher concentration of calcium or cortisone. Maintained sensitivity of D- Ca- Cort+ rats to PTE does not appear to be the consequence of a lesser degree of D-deficiency: the whole body vitamin D pool and its chloroform-soluble fraction in these animals are not different from those of their D- Ca- PTE- unresponsive controls. Repeated PTE injections for 4 days exhaust the sensitivity to the hypercalcemic action of PTE of D- Ca- Cort+ rats. The present data seem to indicate that cortisone-treated D- Ca- rats, responsive to the bone action of PTE, are characterized by a near normal bone calcium content and Ca/P ratio, and a significant increase in the number of osteoclasts.
D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D002118:Calcium / Q000172:deficiency* / Q000378:metabolism; D002452:Cell Count; D003348:Cortisone / Q000494:pharmacology*; D006934:Hypercalcemia / Q000378:metabolism*; D008297:Male; D010010:Osteoclasts; D010280:Parathyroid Glands / Q000502:physiology; D010758:Phosphorus / Q000378:metabolism; D051381:Rats; D014020:Tissue Extracts / Q000494:pharmacology*; D014808:Vitamin D Deficiency / Q000097:blood*
D014020:Tissue Extracts; D010758:Phosphorus; D002118:Calcium; D003348:Cortisone