Biomaterial Database

Circadian rhythms of urea formation and argininosuccinate synthetase activity in rat liver. 1978

H Kato, and M Mizutani-Funahashi, and S Shiosaka, and H Nakagawa

The circadian rhythms of the urea concentrations in urine, serum, and liver and their generation mechanism were investigated. When rats were allowed to eat freely, the urea concentration and the total urea content of the urine were higher during the night than during the day-time. Consistent with these findings, the urea concentrations in the liver and serum had circadian rhythms with the highest values at 0200 hours and the lowest values at 1400 hours. The amplitude of the rhythm increased with increase in the dietary protein (casein) content. Of the five urea cycle enzymes in the liver, only argininosuccinate synthetase showed fluctuation in activity, and this had the same pattern as the circadian rhythms of urea concentrations. These findings suggest that the circadian rhythm of argininosuccinate synthetase in the liver might be directly responsible for the rhythms of change in urea concentrations in the liver, blood and urine. The circadian increase in enzyme activity was inhibited by cycloheximide, but not by actinomycin D.

UI	MeSH Term	Description	Entries
D008025	Ligases	A class of enzymes that catalyze the formation of a bond between two substrate molecules, coupled with the hydrolysis of a pyrophosphate bond in ATP or a similar energy donor. (Dorland, 28th ed) EC 6.	Ligase,Synthetases,Synthetase
D008099	Liver	A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances.	Livers
D008297	Male		Males
D002940	Circadian Rhythm	The regular recurrence, in cycles of about 24 hours, of biological processes or activities, such as sensitivity to drugs or environmental and physiological stimuli.	Diurnal Rhythm,Nyctohemeral Rhythm,Twenty-Four Hour Rhythm,Nycthemeral Rhythm,Circadian Rhythms,Diurnal Rhythms,Nycthemeral Rhythms,Nyctohemeral Rhythms,Rhythm, Circadian,Rhythm, Diurnal,Rhythm, Nycthemeral,Rhythm, Nyctohemeral,Rhythm, Twenty-Four Hour,Rhythms, Circadian,Rhythms, Diurnal,Rhythms, Nycthemeral,Rhythms, Nyctohemeral,Rhythms, Twenty-Four Hour,Twenty Four Hour Rhythm,Twenty-Four Hour Rhythms
D003513	Cycloheximide	Antibiotic substance isolated from streptomycin-producing strains of Streptomyces griseus. It acts by inhibiting elongation during protein synthesis.	Actidione,Cicloheximide
D003609	Dactinomycin	A compound composed of a two CYCLIC PEPTIDES attached to a phenoxazine that is derived from STREPTOMYCES parvullus. It binds to DNA and inhibits RNA synthesis (transcription), with chain elongation more sensitive than initiation, termination, or release. As a result of impaired mRNA production, protein synthesis also declines after dactinomycin therapy. (From AMA Drug Evaluations Annual, 1993, p2015)	Actinomycin,Actinomycin D,Meractinomycin,Cosmegen,Cosmegen Lyovac,Lyovac-Cosmegen,Lyovac Cosmegen,Lyovac, Cosmegen,LyovacCosmegen
D004032	Diet	Regular course of eating and drinking adopted by a person or animal.	Diets
D004044	Dietary Proteins	Proteins obtained from foods. They are the main source of the ESSENTIAL AMINO ACIDS.	Proteins, Dietary,Dietary Protein,Protein, Dietary
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001124	Argininosuccinate Synthase	An enzyme of the urea cycle that catalyzes the formation of argininosuccinic acid from citrulline and aspartic acid in the presence of ATP. Absence or deficiency of this enzyme causes the metabolic disease CITRULLINEMIA in humans. EC 6.3.4.5.	Argininosuccinate Synthetase,Synthase, Argininosuccinate,Synthetase, Argininosuccinate