Maintenance by cortisone of the calcemic response to parathyroid extract of rats on a diet without vitamin D and low in calcium |
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Authors: | Dr. H. Pavlovitch G. Witmer J. Bertret V. Presle S. Balsan |
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Affiliation: | 1. Laboratoire des Tissus Calcifiés (CNRS ER 126) and Unité de Recherches sur les Maladies du Métabolisme chez l’Enfant, H?pital des Enfants Malades, Paris
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Abstract: | 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. |
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Keywords: | Cortisone Vitamin D PTH Rats |
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