Induction of 25-OH-vitamin D3 24- and 23-hydroxylase activities in partially purified renal extracts from pigs given exogenous 1,25-(OH)2D3

Steroids. 1990 Sep;55(9):395-8. doi: 10.1016/0039-128x(90)90097-u.


A renal mitochondrial cytochrome P 450 preparation from pigs treated with exogenous 1,25-(OH)2D3 was reconstituted with an NADPH-generating system, adrenodoxin and adrenodoxin reductase. The reconstituted system catalyzed the conversion of the substrate, 25-OH-D3, to metabolites comigrating with authentic 23,25-(OH)2D3 and 24,25-(OH)2D3 in both straight- and reverse-phase high-performance liquid chromatography systems, which achieve separation of these metabolites from each other as well as from other vitamin D metabolites. The putative 23,25-(OH)2D3 product was resistant to periodate treatment, while the 24,25-(OH)2D3 product was sensitive, providing additional evidence for the identity of the products. Although induction of 24-hydroxylase activity has been studied using renal homogenates from several species, only recently have techniques become available to study the activity of the enzyme in a solubilized and reconstituted form. Using these techniques, the present study shows that production of 24,25-(OH)2D3 was increased more than 80-fold with 1,25-(OH)2D3 treatment compared with untreated controls, an effect much greater than that previously observed with homogenates. In addition, production of both 23,25-(OH)2D3 and 24,25-(OH)2D3 varied with substrate concentration and was consistent with a monooxygenase-linked enzyme reaction.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Calcitriol / pharmacology*
  • Cytochrome P-450 Enzyme System / isolation & purification
  • Enzyme Induction
  • Female
  • Kidney / drug effects*
  • Kidney / enzymology*
  • Male
  • Mitochondria / enzymology
  • Solubility
  • Steroid Hydroxylases / biosynthesis*
  • Steroid Hydroxylases / drug effects
  • Swine
  • Vitamin D / isolation & purification
  • Vitamin D / metabolism
  • Vitamin D3 24-Hydroxylase


  • Vitamin D
  • Cytochrome P-450 Enzyme System
  • Steroid Hydroxylases
  • Vitamin D3 24-Hydroxylase
  • Calcitriol