title: Acute effects of parathyroid extract on renal vitamin D hydroxylases in Japanese quail.
abstract: The dose- and the time-response relationships of parathyroid hormone's modulation of in vitro 1,25-(OH)2D3 and 24,25-(OH)2D3 production in Japanese quail were investigated. 4-week-old female Japanese quail were injected intramuscularly with three different doses (30, 90 and 270 USP units/kg) of parathyroid extract (PTH). 4, 12 and 24 h after the in vivo administration of PTH, kidney homogenates were incubated with tritiated 25-(OH)D3. All three doses of PTH stimulated 1,25-(OH)2D3 and inhibited 24,25-(OH)2D3 production at 12 h relative to the vehicle-treated control group. The responses of the vitamin D hydroxylases were not detectable at 4 h and had returned to control levels by 24 h. Plasma calcium rose significantly at 4 h with the two higher doese of PTH (90 and 270 USP units/mg) but not with the lowest dose. By 12 h the plasma calcium had returned to control levels except at the highest dose of PTH. By 24 h all of the plasma calcium levels had returned to control values. Plasma inorganic phosphate levels were depressed at 4 h by all three PTH doses; they remained depressed at 12 h and returned to control levels by 24 h. It is concluded that the pharmacological effects of PTH on the renal vitamin D hydroxylases are slower in onset and shorter in duration when compared with those of estradiol.
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood; D003370:Coturnix; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006887:Hydroxycholecalciferols / Q000096:biosynthesis; D007273:Injections, Intramuscular; D007668:Kidney / Q000201:enzymology* / Q000378:metabolism; D006899:Mixed Function Oxygenases / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000494:pharmacology*; D010710:Phosphates / Q000097:blood; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D006887:Hydroxycholecalciferols; D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; D004958:Estradiol; D006899:Mixed Function Oxygenases; D002118:Calcium