Synergistic induction of rat hepatic ornithine decarboxylase by multiple doses of cobalt chloride.
The level of rat hepatic ornithine decarboxylase (ODC) induced by repetitive administration of Co2+ was determined by affinity labeling with [3H]difluoromethylornithine. Such a treatment with Co2+ ion induced ODC level to a 10-fold greater extent than single dose of the metal ion or well-known inducers of the enzyme, such as thioacetamide or carbon tetrachloride. The half life of ODC activity induced by repetitive treatment with Co2+ (95 min) was substantially increased to about 10-fold over the value obtained from the enzyme induced by single treatment with the metal ion (10 min). ODC activity induced by repetitive treatment with Co2+ was separated into two peaks by DEAE-Sepharose column chromatography. The two independently collected fractions of ODC peaks exhibited different affinity for pyridoxal 5'-phosphate in vitro and sensitivity to cycloheximide in vivo.
Numazawa
S
S
Department of Biochemical Toxicology, School of Pharmaceutical Sciences, Showa University, Tokyo, Japan.
Oguro
T
T
Yoshida
T
T
Kuroiwa
Y
Y
D000818:Animals; D002251:Carbon Tetrachloride / Q000494:pharmacology; D003035:Cobalt / Q000008:administration & dosage / Q000494:pharmacology*; D003513:Cycloheximide / Q000494:pharmacology; D004334:Drug Administration Schedule; D004357:Drug Synergism; D004790:Enzyme Induction; D007279:Injections, Subcutaneous; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D009955:Ornithine Decarboxylase / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D013853:Thioacetamide / Q000494:pharmacology
D013853:Thioacetamide; D003035:Cobalt; D003513:Cycloheximide; D002251:Carbon Tetrachloride; D009955:Ornithine Decarboxylase; C018021:cobaltous chloride