End product inhibition of hepatic 25-hydroxyvitamin D production in the rat: specificity and kinetics

Journal Article · Fri Nov 01 00:00:00 EST 1985 · Arch. Biochem. Biophys.; (United States)

DOI:https://doi.org/10.1016/0003-9861(85)90234-6· OSTI ID:6037784

Milne, M L; Baran, D T

The role of vitamin D metabolites in the regulation of hepatic 25-hydroxyvitamin D production was investigated by examining the effects of 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, and 24,25-dihydroxyvitamin D on the synthesis of (25-/sup 3/H)hydroxyvitamin D by rachitic rat liver homogenates. Production of (25-/sup 3/H)hydroxyvitamin D was inhibited by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D, but not by 24,25-dihydroxyvitamin D. 25-Hydroxyvitamin D increased the Km of the vitamin D-25-hydroxylase enzyme(s), while 1,25-dihydroxyvitamin D decreased the Vmax with a Ki of 88.7 ng/ml. Inhibition of hepatic 25-hydroxyvitamin D production by 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D may be another control mechanism to regulate circulating vitamin D levels.

• Research Organization: Univ. of Massachusetts Medical Center, Worcester
• OSTI ID: 6037784
• Journal Information: Arch. Biochem. Biophys.; (United States), Vol. 2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
TRITIUM COMPOUNDS
BIOSYNTHESIS
VITAMIN D
BIOCHEMISTRY
KINETICS
LIVER
RATS
RICKETS
ANIMALS
BODY
CHEMISTRY
DIGESTIVE SYSTEM
DISEASES
GLANDS
LABELLED COMPOUNDS
MAMMALS
METABOLIC DISEASES
ORGANS
RODENTS
SKELETAL DISEASES
SYNTHESIS
VERTEBRATES
VITAMINS
550201* - Biochemistry- Tracer Techniques