RESUMO
The metabolism of adenine, hypoxanthine, guanine, and adenosine was studied in rat liver cell suspensions, prepared by collagenase perfusion. Oxygen supply was a critical variable in the preparation and subsequent incubationof the cells, as judged on the basis of the ratio of radioactivity in ATP to that in ADP after incubation with [14C]adenine. This ratio is suggested as an additional criterion of cell function. Adenine nucleotides synthesized from [14C]adenine were slowly catabolized to allantoin, with little incorporationof radioactivity into other purine compounds. [14C]Adenine is thus suitable for prelabelling the adenine nucleotide pool. [14C]Guanine and [14C]hypoxanthine were rapidly catabolized to allantoin, whereas nucleotide synthesis was low. [14C]Adenosine was initially phosphorylated and deaminated at about equal rates, but with continued incubation catabolic products predominated. Isolated hepatocytes were found suitable for studies of purine metabolism, in which the liver has important functions for the whole organism.
Assuntos
Fígado/metabolismo , Purinas/metabolismo , Adenina/metabolismo , Nucleotídeos de Adenina/biossíntese , Adenosina/metabolismo , Alantoína/metabolismo , Animais , Guanina/metabolismo , Nucleotídeos de Guanina/biossíntese , Hipoxantinas/metabolismo , Fígado/citologia , Consumo de Oxigênio , RatosAssuntos
Frutose/metabolismo , Glucose/metabolismo , Nucleotídeos de Adenina/metabolismo , Adulto , Animais , Erros Inatos do Metabolismo dos Carboidratos/metabolismo , Frutose/sangue , Humanos , Infusões Parenterais , Fígado/metabolismo , Masculino , Fosfatos/metabolismo , Ratos , Ácido Úrico/metabolismoAssuntos
Nucleotídeos de Adenina/metabolismo , Frutose/farmacologia , Fígado/efeitos dos fármacos , Trifosfato de Adenosina/metabolismo , Alantoína/biossíntese , Alopurinol/farmacologia , Animais , Depressão Química , Etanol/farmacologia , Feminino , Frutose/administração & dosagem , Galactose/farmacologia , Glucose/farmacologia , Hexoses/farmacologia , Técnicas In Vitro , Injeções Intravenosas , Rim/metabolismo , Lactatos/metabolismo , Lactatos/farmacologia , Manose/farmacologia , Miocárdio/metabolismo , Perfusão , Fosfatos/metabolismo , Purinas/metabolismo , Piruvatos/metabolismo , Ratos , Ribose/farmacologia , Sorbitol/farmacologia , Sorbose/farmacologia , Fatores de Tempo , Ácido Úrico/biossínteseAssuntos
Erros Inatos do Metabolismo dos Aminoácidos/enzimologia , Fígado/enzimologia , Erros Inatos do Metabolismo/enzimologia , Transaminases/metabolismo , Adulto , Idoso , Criança , Pré-Escolar , Feminino , Feto , Humanos , Lactente , Recém-Nascido , Cetoácidos , Cinética , Fígado/embriologia , Pessoa de Meia-Idade , Ornitina/sangue , Ornitina/metabolismo , Ornitina Carbamoiltransferase/metabolismo , Gravidez , Proteínas/metabolismoAssuntos
Alimentos , Fenômenos Fisiológicos da Nutrição do Lactente , Fatores Etários , Aminoácidos , Calorimetria , Carboidratos , Ácidos Graxos Essenciais , Crescimento , Humanos , Lactente , Alimentos Infantis , Ácidos Linoleicos , Lipídeos , Metabolismo , Necessidades Nutricionais , Nutrição Parenteral , Proteínas , VitaminasRESUMO
Intravenous administration of D-fructose to rats rapidly depletes liver adenosine triphosphate and inorganic phosphate; marked elevations of uric acid and allantoin in plasma follow. Concomitantly the incorporation of DL-leucine-1-(14)C into liver protein is almost completely inhibited.
Assuntos
Trifosfato de Adenosina/metabolismo , Frutose/farmacologia , Fígado/metabolismo , Fosfatos/metabolismo , Biossíntese de Proteínas , Nucleotídeos de Adenina/análise , Alantoína/sangue , Animais , Erros Inatos do Metabolismo dos Carboidratos , Isótopos de Carbono , Depressão Química , Leucina/metabolismo , Fígado/análise , Fígado/efeitos dos fármacos , Ratos , Estereoisomerismo , Ácido Úrico/sangueRESUMO
1. During the normal development of the rat, the specific activity of liver ornithine-keto acid aminotransferase exhibits a transient elevation around term, and subsequently increases to adult activity levels during the third postnatal week. 2. The synthetic glucocorticoid triamcinolone, administered as a single injection, produces a marked elevation of the ornithine-keto acid aminotransferase activity within 24hr. if given postnatally before the natural increase in ornithine-keto acid aminotransferase activity has occurred. In foetal and adult animals, triamcinolone does not induce any increase in this enzyme activity. 3. The repeated administration of puromycin completely prevents the rise in ornithine-keto acid aminotransferase activity that follows triamcinolone administration. 4. If adult rats are fed with a protein-free carbohydrate diet, or one free of arginine, the ornithine-keto acid aminotransferase activity diminishes to a fraction of the normal. When such diets are given, a single injection of triamcinolone does not increase the enzyme activity within 24hr. 5. Partial hepatectomy, and repeated injections of growth hormone, depress the ornithine-keto acid aminotransferase activity in adult rats. 6. The findings are discussed in relation to the mechanisms concerned with developmental and adaptive changes in enzyme activities in the liver.
