24,25(OH)2D3 enhances the calcemic effect of 1,25(OH)2D3 in PTX rats.
The effect of 24,25(OH)2D3 on 1,25(OH)2D3-induced hypercalcemia was studied in parathyroidectomized (PTX) rats for 10 days. Serum (S) and urinary Ca excretion (UCaV) were measured in (a) control rats, (b) rats receiving a daily sc injection of 54 ng 1,25(OH)2D3, (c) rats receiving 24,25(OH)2D3 in the same dose and same manner, and (d) rats receiving 1,25(OH)2D3 + 24,25(OH)2D3. Our results show that (i) 24,25(OH)2D3 alone does not increase SCa2+ in PTX rats, (ii) combined administration of 1,25(OH)2D3 + 24,25(OH)2D3 enhances the hypercalcemic response to 1,25(OH)2D3 without a parallel increase in UCaV, (iii) combined administration of 1,25(OH)2D3 + 24,25(OH)2D3 reduces the rise in urinary excretion of Ca2+ compared with that of rats receiving 1,25(OH)2D3 alone for 10 days, and (iv) these alterations are independent of parathyroid hormone.
D015650:24,25-Dihydroxyvitamin D 3; D000818:Animals; D002117:Calcitriol / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D003404:Creatinine / Q000097:blood; D004100:Dihydroxycholecalciferols / Q000494:pharmacology*; D004231:Diuresis; D004327:Drinking Behavior / Q000187:drug effects; D004357:Drug Synergism; D004435:Eating / Q000187:drug effects; D008297:Male; D010280:Parathyroid Glands / Q000502:physiology*; D010281:Parathyroid Hormone / Q000502:physiology; D010710:Phosphates / Q000652:urine; D051381:Rats; D013965:Thyroidectomy
D004100:Dihydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D015650:24,25-Dihydroxyvitamin D 3; D003404:Creatinine; D002117:Calcitriol; D002118:Calcium